Improve error messages

Logic/Tags/TagUtils.ts

@@ -286,7 +286,7 @@ export class TagUtils {
     private static TagUnsafe(json: AndOrTagConfigJson | string, context: string = ""): TagsFilter {
 
         if (json === undefined) {
-            throw `Error while parsing a tag: 'json' is undefined in ${context}. Make sure all the tags are defined and at least one tag is present in a complex expression`
+            throw new Error(`Error while parsing a tag: 'json' is undefined in ${context}. Make sure all the tags are defined and at least one tag is present in a complex expression`)
         }
         if (typeof (json) != "string") {
             if (json.and !== undefined && json.or !== undefined) {

Models/ThemeConfig/Conversion/Conversion.ts

@@ -226,7 +226,7 @@ export class Fuse<T> extends DesugaringStep<T> {
                     break;
                 }
             }catch(e){
-                console.error("Step "+step.name+" failed due to "+e);
+                console.error("Step "+step.name+" failed due to ",e,e.stack);
                 throw e
             }
         }

Models/ThemeConfig/Conversion/Validation.ts

@@ -321,8 +321,9 @@ export class DetectShadowedMappings extends DesugaringStep<QuestionableTagRender
         for (const calculatedTagName of this._calculatedTagNames) {
             defaultProperties[calculatedTagName] = "some_calculated_tag_value_for_"+calculatedTagName
         }
-        const parsedConditions = json.mappings.map(m => {
+        const parsedConditions = json.mappings.map((m,i) => {
-            const ifTags = TagUtils.Tag(m.if);
+            const ctx = `${context}.mappings[${i}]`
+            const ifTags = TagUtils.Tag(m.if, ctx);
             if(m.hideInAnswer !== undefined && m.hideInAnswer !== false && m.hideInAnswer !== true){
                 let conditionTags = TagUtils.Tag( m.hideInAnswer)
                 // Merge the condition too!
@@ -407,7 +408,7 @@ export class DetectMappingsWithImages extends DesugaringStep<TagRenderingConfigJ
 
             const mapping = json.mappings[i]
             const ignore = mapping["#"]?.indexOf(ignoreToken) >=0
-            const images = Utils.Dedup(Translations.T(mapping.then).ExtractImages())
+            const images = Utils.Dedup(Translations.T(mapping.then)?.ExtractImages() ?? [])
             const ctx = `${context}.mappings[${i}]`
             if (images.length > 0) {
                 if(!ignore){

Models/ThemeConfig/Json/LayerConfigJson.ts

@@ -287,7 +287,7 @@ export interface LayerConfigJson {
      */
     tagRenderings?:
         (string
-            | { builtin: string, override: any }
+            | { builtin: string | string[], override: any }
             | QuestionableTagRenderingConfigJson
             | RewritableConfigJson<(string | { builtin: string, override: any } | QuestionableTagRenderingConfigJson)[]>
             ) [],

Models/ThemeConfig/TagRenderingConfig.ts

@@ -172,15 +172,21 @@ export default class TagRenderingConfig {
             this.mappings = json.mappings.map((mapping, i) => {
 
                 const ctx = `${translationKey}.mappings.${i}`
+                if (mapping.if === undefined) {
+                    throw `${ctx}: Invalid mapping: "if" is not defined in ${JSON.stringify(mapping)}`
+                }
                 if (mapping.then === undefined) {
-                    throw `${ctx}: Invalid mapping: if without body`
+                    if(mapping["render"] !== undefined){
+                        throw `${ctx}: Invalid mapping: no 'then'-clause found. You might have typed 'render' instead of 'then', change it in ${JSON.stringify(mapping)}`
+                    }
+                    throw `${ctx}: Invalid mapping: no 'then'-clause found in ${JSON.stringify(mapping)}`
                 }
                 if (mapping.ifnot !== undefined && !this.multiAnswer) {
-                    throw `${ctx}: Invalid mapping: ifnot defined, but the tagrendering is not a multianswer`
+                    throw `${ctx}: Invalid mapping: 'ifnot' is defined, but the tagrendering is not a multianswer. Either remove ifnot or set 'multiAnswer:true' to enable checkboxes instead of radiobuttons`
                 }
 
-                if (mapping.if === undefined) {
+                if(mapping["render"] !== undefined){
-                    throw `${ctx}: Invalid mapping: "if" is not defined, but the tagrendering is not a multianswer`
+                    throw `${ctx}: Invalid mapping: a 'render'-key is present, this is probably a bug: ${JSON.stringify(mapping)}`
                 }
                 if (typeof mapping.if !== "string" && mapping.if["length"] !== undefined) {
                     throw `${ctx}: Invalid mapping: "if" is defined as an array. Use {"and": <your conditions>} or {"or": <your conditions>} instead`