diff --git a/Logic/DetermineLayout.ts b/Logic/DetermineLayout.ts
index 744198296..c58012c69 100644
--- a/Logic/DetermineLayout.ts
+++ b/Logic/DetermineLayout.ts
@@ -19,6 +19,7 @@ import {PrepareTheme} from "../Models/ThemeConfig/Conversion/PrepareTheme";
 import * as licenses from "../assets/generated/license_info.json"
 import TagRenderingConfig from "../Models/ThemeConfig/TagRenderingConfig";
 import {FixImages} from "../Models/ThemeConfig/Conversion/FixImages";
+import Svg from "../Svg";
 
 export default class DetermineLayout {
 
@@ -73,6 +74,8 @@ export default class DetermineLayout {
         userLayoutParam: UIEventSource<string>
     ): LayoutConfig | null {
         let hash = location.hash.substr(1);
+        let json: any;
+
         try {
             // layoutFromBase64 contains the name of the theme. This is partly to do tracking with goat counter
             const dedicatedHashFromLocalStorage = LocalStorageSource.Get(
@@ -95,7 +98,6 @@ export default class DetermineLayout {
                 dedicatedHashFromLocalStorage.setData(hash);
             }
 
-            let json: any;
             try {
                 json = JSON.parse(atob(hash));
             } catch (e) {
@@ -115,23 +117,26 @@ export default class DetermineLayout {
         } catch (e) {
             console.error(e)
             if (hash === undefined || hash.length < 10) {
-                DetermineLayout.ShowErrorOnCustomTheme("Could not load a theme from the hash", new FixedUiElement("Hash does not contain data"))
+                DetermineLayout.ShowErrorOnCustomTheme("Could not load a theme from the hash", new FixedUiElement("Hash does not contain data"), json)
             }
-            this.ShowErrorOnCustomTheme("Could not parse the hash", new FixedUiElement(e))
+            this.ShowErrorOnCustomTheme("Could not parse the hash", new FixedUiElement(e), json)
             return null;
         }
     }
 
     public static ShowErrorOnCustomTheme(
         intro: string = "Error: could not parse the custom layout:",
-        error: BaseUIElement) {
+        error: BaseUIElement,
+        json?: any) {
         new Combine([
             intro,
             error.SetClass("alert"),
-            new SubtleButton("./assets/svg/mapcomplete_logo.svg",
+            new SubtleButton(Svg.back_svg(),
                 "Go back to the theme overview",
-                {url: window.location.protocol + "//" + window.location.hostname + "/index.html", newTab: false})
-
+                {url: window.location.protocol + "//" + window.location.hostname + "/index.html", newTab: false}),
+            json !== undefined ? new SubtleButton(Svg.download_svg(),"Download the JSON file").onClick(() => {
+                Utils.offerContentsAsDownloadableFile(JSON.stringify(json, null, "  "), "theme_definition.json")
+            }) : undefined
         ])
             .SetClass("flex flex-col clickable")
             .AttachTo("centermessage");
@@ -189,7 +194,8 @@ export default class DetermineLayout {
                 console.error(e)
                 DetermineLayout.ShowErrorOnCustomTheme(
                     `<a href="${link}">${link}</a> is invalid:`,
-                    new FixedUiElement(e)
+                    new FixedUiElement(e),
+                    parsed
                 )
                 return null;
             }
diff --git a/Logic/ExtraFunctions.ts b/Logic/ExtraFunctions.ts
index 242e323e8..9a97ff39e 100644
--- a/Logic/ExtraFunctions.ts
+++ b/Logic/ExtraFunctions.ts
@@ -413,7 +413,6 @@ export class ExtraFunctions {
 
         const elems = []
         for (const func of ExtraFunctions.allFuncs) {
-            console.log("Generating ", func.constructor.name)
             elems.push(new Title(func._name, 3),
                 func._doc,
                 new List(func._args ?? [], true))
diff --git a/Logic/ImageProviders/ImageProvider.ts b/Logic/ImageProviders/ImageProvider.ts
index c1d90578e..dded72a0b 100644
--- a/Logic/ImageProviders/ImageProvider.ts
+++ b/Logic/ImageProviders/ImageProvider.ts
@@ -35,7 +35,7 @@ export default abstract class ImageProvider {
     }): UIEventSource<ProvidedImage[]> {
         const prefixes = options?.prefixes ?? this.defaultKeyPrefixes
         if (prefixes === undefined) {
-            throw "The image provider" + this.constructor.name + " doesn't define `defaultKeyPrefixes`"
+            throw "No `defaultKeyPrefixes` defined by this image provider"
         }
         const relevantUrls = new UIEventSource<{ url: string; key: string; provider: ImageProvider }[]>([])
         const seenValues = new Set<string>()
diff --git a/Logic/Osm/Actions/OsmChangeAction.ts b/Logic/Osm/Actions/OsmChangeAction.ts
index 120870f73..1754a91bc 100644
--- a/Logic/Osm/Actions/OsmChangeAction.ts
+++ b/Logic/Osm/Actions/OsmChangeAction.ts
@@ -23,7 +23,7 @@ export default abstract class OsmChangeAction {
 
     public Perform(changes: Changes) {
         if (this.isUsed) {
-            throw "This ChangeAction is already used: " + this.constructor.name
+            throw "This ChangeAction is already used"
         }
         this.isUsed = true;
         return this.CreateChangeDescriptions(changes)
diff --git a/Models/ThemeConfig/Conversion/Conversion.ts b/Models/ThemeConfig/Conversion/Conversion.ts
index d90bfca0b..2926fb3de 100644
--- a/Models/ThemeConfig/Conversion/Conversion.ts
+++ b/Models/ThemeConfig/Conversion/Conversion.ts
@@ -12,10 +12,10 @@ export abstract class Conversion<TIn, TOut> {
     protected readonly doc: string;
     public readonly name: string
     
-    constructor(doc: string, modifiedAttributes: string[] = [], name?: string) {
+    constructor(doc: string, modifiedAttributes: string[] = [], name: string) {
         this.modifiedAttributes = modifiedAttributes;
         this.doc = doc + "\n\nModified attributes are\n" + modifiedAttributes.join(", ");
-        this.name = name ?? this.constructor.name
+        this.name = name 
     }
 
     public static strict<T>(fixed: { errors?: string[], warnings?: string[], information?: string[], result?: T }): T {
@@ -94,8 +94,8 @@ export class OnEveryConcat<X, T> extends DesugaringStep<T> {
     private readonly step: Conversion<X, X[]>;
 
     constructor(key: string, step: Conversion<X, X[]>) {
-        super(`Applies ${step.constructor.name} onto every object of the list \`${key}\`. The results are concatenated and used as new list`, [key], 
-            "OnEveryConcat("+step.name+")");
+        super(`Applies ${step.name} onto every object of the list \`${key}\`. The results are concatenated and used as new list`, [key], 
+            "OnEvery("+key+").Concat("+step.name+")");
         this.step = step;
         this.key = key;
     }
@@ -126,8 +126,9 @@ export class Fuse<T> extends DesugaringStep<T> {
     private readonly steps: DesugaringStep<T>[];
 
     constructor(doc: string, ...steps: DesugaringStep<T>[]) {
-        super((doc ?? "") + "This fused pipeline of the following steps: " + steps.map(s => s.constructor.name).join(", "),
-            Utils.Dedup([].concat(...steps.map(step => step.modifiedAttributes)))
+        super((doc ?? "") + "This fused pipeline of the following steps: " + steps.map(s => s.name).join(", "),
+            Utils.Dedup([].concat(...steps.map(step => step.modifiedAttributes))),
+            "Fuse of "+steps.map(s => s.name).join(", ")
         );
         this.steps = steps;
     }
@@ -163,7 +164,7 @@ export class SetDefault<T> extends DesugaringStep<T> {
     private readonly _overrideEmptyString: boolean;
 
     constructor(key: string, value: any, overrideEmptyString = false) {
-        super("Sets " + key + " to a default value if undefined");
+        super("Sets " + key + " to a default value if undefined", [], "SetDefault of "+key);
         this.key = key;
         this.value = value;
         this._overrideEmptyString = overrideEmptyString;
diff --git a/Models/ThemeConfig/Conversion/CreateNoteImportLayer.ts b/Models/ThemeConfig/Conversion/CreateNoteImportLayer.ts
index c51437d7f..49d7af5b9 100644
--- a/Models/ThemeConfig/Conversion/CreateNoteImportLayer.ts
+++ b/Models/ThemeConfig/Conversion/CreateNoteImportLayer.ts
@@ -16,7 +16,7 @@ export default class CreateNoteImportLayer extends Conversion<LayerConfigJson, L
         super([
             "Advanced conversion which deducts a layer showing all notes that are 'importable' (i.e. a note that contains a link to some MapComplete theme, with hash '#import').",
             "The import buttons and matches will be based on the presets of the given theme",
-        ].join("\n\n"), [])
+        ].join("\n\n"), [],"CreateNoteImportLayer")
         this._includeClosedNotesDays = includeClosedNotesDays;
     }
 
diff --git a/Models/ThemeConfig/Conversion/FixImages.ts b/Models/ThemeConfig/Conversion/FixImages.ts
index 31d1cfbcd..9e47e126d 100644
--- a/Models/ThemeConfig/Conversion/FixImages.ts
+++ b/Models/ThemeConfig/Conversion/FixImages.ts
@@ -6,7 +6,7 @@ import * as tagrenderingmetapaths from "../../../assets/tagrenderingconfigmeta.j
 
 export class ExtractImages extends Conversion<LayoutConfigJson, string[]> {
     constructor() {
-        super("Extract all images from a layoutConfig using the meta paths");
+        super("Extract all images from a layoutConfig using the meta paths",[],"ExctractImages");
     }
 
     convert(json: LayoutConfigJson, context: string): { result: string[], errors: string[] } {
@@ -62,7 +62,7 @@ export class FixImages extends DesugaringStep<LayoutConfigJson> {
     private readonly _knownImages: Set<string>;
 
     constructor(knownImages: Set<string>) {
-        super("Walks over the entire theme and replaces images to the relative URL. Only works if the ID of the theme is an URL");
+        super("Walks over the entire theme and replaces images to the relative URL. Only works if the ID of the theme is an URL",[],"fixImages");
         this._knownImages = knownImages;
     }
 
diff --git a/Models/ThemeConfig/Conversion/LegacyJsonConvert.ts b/Models/ThemeConfig/Conversion/LegacyJsonConvert.ts
index cf89a5172..f5a5294fb 100644
--- a/Models/ThemeConfig/Conversion/LegacyJsonConvert.ts
+++ b/Models/ThemeConfig/Conversion/LegacyJsonConvert.ts
@@ -8,7 +8,8 @@ export class UpdateLegacyLayer extends DesugaringStep<LayerConfigJson | string |
 
     constructor() {
         super("Updates various attributes from the old data format to the new to provide backwards compatibility with the formats",
-            ["overpassTags", "source.osmtags", "tagRenderings[*].id", "mapRendering"]);
+            ["overpassTags", "source.osmtags", "tagRenderings[*].id", "mapRendering"],
+            "UpdateLegacyLayer");
     }
 
     convert(json: LayerConfigJson, context: string): { result: LayerConfigJson; errors: string[]; warnings: string[] } {
@@ -120,7 +121,7 @@ export class UpdateLegacyLayer extends DesugaringStep<LayerConfigJson | string |
 
 class UpdateLegacyTheme extends DesugaringStep<LayoutConfigJson> {
     constructor() {
-        super("Small fixes in the theme config", ["roamingRenderings"]);
+        super("Small fixes in the theme config", ["roamingRenderings"],"UpdateLegacyTheme");
     }
 
     convert(json: LayoutConfigJson, context: string): { result: LayoutConfigJson; errors: string[]; warnings: string[] } {
diff --git a/Models/ThemeConfig/Conversion/PrepareLayer.ts b/Models/ThemeConfig/Conversion/PrepareLayer.ts
index 94b664df0..673e131e8 100644
--- a/Models/ThemeConfig/Conversion/PrepareLayer.ts
+++ b/Models/ThemeConfig/Conversion/PrepareLayer.ts
@@ -8,7 +8,7 @@ import {Translation} from "../../../UI/i18n/Translation";
 class ExpandTagRendering extends Conversion<string | TagRenderingConfigJson | { builtin: string | string[], override: any }, TagRenderingConfigJson[]> {
     private readonly _state: DesugaringContext;
     constructor(state: DesugaringContext) {
-        super("Converts a tagRenderingSpec into the full tagRendering", []);
+        super("Converts a tagRenderingSpec into the full tagRendering", [],"ExpandTagRendering");
         this._state = state;
     }
 
@@ -147,7 +147,8 @@ class ExpandGroupRewrite extends Conversion<{
 
     constructor(state: DesugaringContext) {
         super(
-            "Converts a rewrite config for tagRenderings into the expanded form"
+            "Converts a rewrite config for tagRenderings into the expanded form",[],
+            "ExpandGroupRewrite"
         );
         this._expandSubTagRenderings = new ExpandTagRendering(state)
     }
diff --git a/Models/ThemeConfig/Conversion/PrepareTheme.ts b/Models/ThemeConfig/Conversion/PrepareTheme.ts
index f2270c014..17e04ac5a 100644
--- a/Models/ThemeConfig/Conversion/PrepareTheme.ts
+++ b/Models/ThemeConfig/Conversion/PrepareTheme.ts
@@ -16,7 +16,7 @@ class SubstituteLayer extends Conversion<(string | LayerConfigJson), LayerConfig
     constructor(
         state: DesugaringContext,
     ) {
-        super("Converts the identifier of a builtin layer into the actual layer, or converts a 'builtin' syntax with override in the fully expanded form", []);
+        super("Converts the identifier of a builtin layer into the actual layer, or converts a 'builtin' syntax with override in the fully expanded form", [],"SubstuteLayers");
         this._state = state;
     }
     
@@ -130,7 +130,7 @@ class AddDefaultLayers extends DesugaringStep<LayoutConfigJson> {
     private _state: DesugaringContext;
 
     constructor(state: DesugaringContext) {
-        super("Adds the default layers, namely: " + Constants.added_by_default.join(", "), ["layers"]);
+        super("Adds the default layers, namely: " + Constants.added_by_default.join(", "), ["layers"],"AddDefaultLayers");
         this._state = state;
     }
 
@@ -182,7 +182,7 @@ class AddDefaultLayers extends DesugaringStep<LayoutConfigJson> {
 
 class AddImportLayers extends DesugaringStep<LayoutConfigJson> {
     constructor() {
-        super("For every layer in the 'layers'-list, create a new layer which'll import notes. (Note that priviliged layers and layers which have a geojson-source set are ignored)", ["layers"]);
+        super("For every layer in the 'layers'-list, create a new layer which'll import notes. (Note that priviliged layers and layers which have a geojson-source set are ignored)", ["layers"],"AddImportLayers");
     }
 
     convert(json: LayoutConfigJson, context: string): { result: LayoutConfigJson; errors: string[] } {
@@ -240,7 +240,7 @@ class AddImportLayers extends DesugaringStep<LayoutConfigJson> {
 export class AddMiniMap extends DesugaringStep<LayerConfigJson> {
     private readonly _state: DesugaringContext;
     constructor(state: DesugaringContext, ) {
-        super("Adds a default 'minimap'-element to the tagrenderings if none of the elements define such a minimap", ["tagRenderings"]);
+        super("Adds a default 'minimap'-element to the tagrenderings if none of the elements define such a minimap", ["tagRenderings"],"AddMiniMap");
         this._state = state;
     }
 
@@ -291,7 +291,7 @@ export class AddMiniMap extends DesugaringStep<LayerConfigJson> {
 class ApplyOverrideAll extends DesugaringStep<LayoutConfigJson> {
 
     constructor() {
-        super("Applies 'overrideAll' onto every 'layer'. The 'overrideAll'-field is removed afterwards", ["overrideAll", "layers"]);
+        super("Applies 'overrideAll' onto every 'layer'. The 'overrideAll'-field is removed afterwards", ["overrideAll", "layers"],"ApplyOverrideAll");
     }
 
     convert(json: LayoutConfigJson, context: string): { result: LayoutConfigJson; errors: string[]; warnings: string[] } {
@@ -321,7 +321,7 @@ class ApplyOverrideAll extends DesugaringStep<LayoutConfigJson> {
 class AddDependencyLayersToTheme extends DesugaringStep<LayoutConfigJson> {
     private readonly _state: DesugaringContext;
     constructor(state: DesugaringContext, ) {
-        super("If a layer has a dependency on another layer, these layers are added automatically on the theme. (For example: defibrillator depends on 'walls_and_buildings' to snap onto. This layer is added automatically)", ["layers"]);
+        super("If a layer has a dependency on another layer, these layers are added automatically on the theme. (For example: defibrillator depends on 'walls_and_buildings' to snap onto. This layer is added automatically)", ["layers"],"AddDependencyLayersToTheme");
         this._state = state;
     }
 
diff --git a/Models/ThemeConfig/Conversion/Validation.ts b/Models/ThemeConfig/Conversion/Validation.ts
index 777e9c614..c28886088 100644
--- a/Models/ThemeConfig/Conversion/Validation.ts
+++ b/Models/ThemeConfig/Conversion/Validation.ts
@@ -16,7 +16,7 @@ class ValidateLanguageCompleteness extends DesugaringStep<any> {
     private readonly _languages: string[];
 
     constructor(...languages: string[]) {
-        super("Checks that the given object is fully translated in the specified languages", []);
+        super("Checks that the given object is fully translated in the specified languages", [], "ValidateLanguageCompleteness");
         this._languages = languages;
     }
 
@@ -25,7 +25,7 @@ class ValidateLanguageCompleteness extends DesugaringStep<any> {
         const translations = Translation.ExtractAllTranslationsFrom(
             obj
         )
-        for (const neededLanguage of this._languages) {
+        for (const neededLanguage of this._languages ?? ["en"]) {
             translations
                 .filter(t => t.tr.translations[neededLanguage] === undefined && t.tr.translations["*"] === undefined)
                 .forEach(missing => {
@@ -50,7 +50,7 @@ class ValidateTheme extends DesugaringStep<LayoutConfigJson> {
     private readonly _isBuiltin: boolean;
 
     constructor(knownImagePaths: Set<string>, path: string, isBuiltin: boolean) {
-        super("Doesn't change anything, but emits warnings and errors", []);
+        super("Doesn't change anything, but emits warnings and errors", [],"ValidateTheme");
         this.knownImagePaths = knownImagePaths;
         this._path = path;
         this._isBuiltin = isBuiltin;
@@ -164,7 +164,7 @@ export class ValidateThemeAndLayers extends Fuse<LayoutConfigJson> {
 class OverrideShadowingCheck extends DesugaringStep<LayoutConfigJson> {
 
     constructor() {
-        super("Checks that an 'overrideAll' does not override a single override");
+        super("Checks that an 'overrideAll' does not override a single override",[],"OverrideShadowingCheck");
     }
 
     convert(json: LayoutConfigJson, context: string): { result: LayoutConfigJson; errors?: string[]; warnings?: string[] } {
@@ -204,7 +204,7 @@ export class PrevalidateTheme extends Fuse<LayoutConfigJson> {
 
 export class DetectShadowedMappings extends DesugaringStep<TagRenderingConfigJson> {
     constructor() {
-        super("Checks that the mappings don't shadow each other");
+        super("Checks that the mappings don't shadow each other",[],"DetectShadowedMappings");
     }
 
     convert(json: TagRenderingConfigJson, context: string): { result: TagRenderingConfigJson; errors?: string[]; warnings?: string[] } {
@@ -254,7 +254,7 @@ export class ValidateLayer extends DesugaringStep<LayerConfigJson> {
     private readonly _isBuiltin: boolean;
 
     constructor(knownImagePaths: Set<string>, path: string, isBuiltin: boolean) {
-        super("Doesn't change anything, but emits warnings and errors", []);
+        super("Doesn't change anything, but emits warnings and errors", [],"ValidateLayer");
         this.knownImagePaths = knownImagePaths;
         this._path = path;
         this._isBuiltin = isBuiltin;
diff --git a/UI/BaseUIElement.ts b/UI/BaseUIElement.ts
index 61d55c251..2157fb2f1 100644
--- a/UI/BaseUIElement.ts
+++ b/UI/BaseUIElement.ts
@@ -102,11 +102,6 @@ export default abstract class BaseUIElement {
             return this._constructedHtmlElement
         }
 
-        if (this.InnerConstructElement === undefined) {
-            throw "ERROR! This is not a correct baseUIElement: " + this.constructor.name
-        }
-
-
         try {
             const el = this.InnerConstructElement();
 
@@ -152,7 +147,7 @@ export default abstract class BaseUIElement {
     }
 
     public AsMarkdown(): string {
-        throw "AsMarkdown is not implemented by " + this.constructor.name + "; implement it in the subclass"
+        throw "AsMarkdown is not implemented; implement it in the subclass"
     }
 
     public Destroy() {
diff --git a/scripts/generateCache.ts b/scripts/generateCache.ts
index da36e76df..36f3303ce 100644
--- a/scripts/generateCache.ts
+++ b/scripts/generateCache.ts
@@ -458,11 +458,13 @@ export async function main(args: string[]) {
 
 
 let args = [...process.argv]
-args.splice(0, 2)
-try {
-    main(args)
-        .then(() => console.log("All done!"))
-        .catch(e => console.error("Error building cache:", e));
-} catch (e) {
-    console.error("Error building cache:", e)
-}
\ No newline at end of file
+if (!args[1]?.endsWith("test/TestAll.ts")) {
+    args.splice(0, 2)
+    try {
+        main(args)
+            .then(() => console.log("All done!"))
+            .catch(e => console.error("Error building cache:", e));
+    } catch (e) {
+        console.error("Error building cache:", e)
+    }
+}
diff --git a/test/CodeQuality.spec.ts b/test/CodeQuality.spec.ts
new file mode 100644
index 000000000..53fe24587
--- /dev/null
+++ b/test/CodeQuality.spec.ts
@@ -0,0 +1,36 @@
+import T from "./TestHelper";
+import {exec} from "child_process";
+
+export default class CodeQualitySpec extends T {
+    constructor() {
+        super([
+            [
+                "no constructor.name in compiled code", () => {
+
+                const excludedDirs = [".git", "node_modules", "dist", ".cache", ".parcel-cache", "assets"]
+
+                exec("grep \"constructor.name\" -r . " + excludedDirs.map(d => "--exclude-dir=" + d).join(" "), ((error, stdout, stderr) => {
+                    console.log("Grep gave: ", stdout)
+                    if (error?.message?.startsWith("Command failed: grep")) {
+                        return;
+                    }
+                    if (error !== null) {
+                        throw error
+
+                    }
+                    if (stderr !== "") {
+                        throw stderr
+                    }
+
+                    const found = stdout.split("\n").filter(s => s !== "").filter(s => s.startsWith("test/"));
+                    if (found.length > 0) {
+                        throw "Found a 'constructor.name' at " + found.join(", ") + ". This is not allowed, as minification does erase names."
+                    }
+
+                }))
+
+            }
+            ]
+        ]);
+    }
+}
\ No newline at end of file
diff --git a/test/TestAll.ts b/test/TestAll.ts
index 8251c4fab..28cf24b54 100644
--- a/test/TestAll.ts
+++ b/test/TestAll.ts
@@ -18,6 +18,7 @@ import LegacyThemeLoaderSpec from "./LegacyThemeLoader.spec";
 import T from "./TestHelper";
 import CreateNoteImportLayerSpec from "./CreateNoteImportLayer.spec";
 import CreateCacheSpec from "./CreateCache.spec";
+import CodeQualitySpec from "./CodeQuality.spec";
 
 
 async function main() {
@@ -39,7 +40,8 @@ async function main() {
         new ReplaceGeometrySpec(),
         new LegacyThemeLoaderSpec(),
         new CreateNoteImportLayerSpec(),
-        new CreateCacheSpec()
+        new CreateCacheSpec(),
+        new CodeQualitySpec()
     ]
     ScriptUtils.fixUtils();
     const realDownloadFunc = Utils.externalDownloadFunction;