Improve error message when merging an override fails

src/Models/ThemeConfig/Conversion/ConversionContext.ts

@@ -1,4 +1,5 @@
 import { ConversionMessage, ConversionMsgLevel } from "./Conversion"
+import { Utils } from "../../../Utils"
 
 export class ConversionContext {
     private static reported = false
@@ -148,4 +149,18 @@ export class ConversionContext {
     debug(message: string) {
         this.messages.push({ context: this, level: "debug", message })
     }
+
+    /**
+     * Exactly the same as Utils.Merge, except that it wraps the error message
+     * @param source
+     * @param target
+     * @constructor
+     */
+    MergeObjectsForOverride<T, S>(source: Readonly<S>, target: T): T & S {
+        try{
+            return Utils.Merge(source,target)
+        }catch (e) {
+            this.err("Could not apply an override: due to "+e+"\n\tHINT: did you just pull changes from the repository or switch branches? Try 'npm run reset:layeroverview'")
+        }
+    }
 }

src/Models/ThemeConfig/Conversion/PrepareLayer.ts

@@ -212,7 +212,7 @@ class ExpandTagRendering extends Conversion<
         return result
     }
 
-    private lookup(name: string): TagRenderingConfigJson[] | undefined {
+    private lookup(name: string, ctx: ConversionContext): TagRenderingConfigJson[] | undefined {
         const direct = this.directLookup(name)
 
         if (direct === undefined) {
@@ -224,13 +224,13 @@ class ExpandTagRendering extends Conversion<
             if (nm !== undefined) {
                 let indirect: TagRenderingConfigJson[]
                 if (typeof nm === "string") {
-                    indirect = this.lookup(nm)
+                    indirect = this.lookup(nm, ctx)
                 } else {
-                    indirect = [].concat(...nm.map((n) => this.lookup(n)))
+                    indirect = [].concat(...nm.map((n) => this.lookup(n, ctx)))
                 }
                 for (let foundTr of indirect) {
                     foundTr = Utils.Clone<any>(foundTr)
-                    Utils.Merge(tagRenderingConfigJson["override"] ?? {}, foundTr)
+                    ctx.Merge(tagRenderingConfigJson["override"] ?? {}, foundTr)
                     foundTr["id"] = tagRenderingConfigJson["id"] ?? foundTr["id"]
                     result.push(foundTr)
                 }
@@ -318,7 +318,7 @@ class ExpandTagRendering extends Conversion<
         if (typeof tr === "string") {
             let lookup
             if (this._state.tagRenderings !== null) {
-                lookup = this.lookup(tr)
+                lookup = this.lookup(tr, ctx)
             }
             if (lookup === undefined) {
                 if (
@@ -382,7 +382,7 @@ class ExpandTagRendering extends Conversion<
 
             const trs: TagRenderingConfigJson[] = []
             for (const name of names) {
-                const lookup = this.lookup(name)
+                const lookup = this.lookup(name, ctx)
                 if (lookup === undefined) {
                     let candidates = Array.from(state.tagRenderings.keys())
                     if (name.indexOf(".") > 0) {
@@ -433,7 +433,7 @@ class ExpandTagRendering extends Conversion<
                 }
                 for (let foundTr of lookup) {
                     foundTr = Utils.Clone<any>(foundTr)
-                    Utils.Merge(tr["override"] ?? {}, foundTr)
+                    ctx.MergeObjectsForOverride(tr["override"] ?? {}, foundTr)
                     if (names.length == 1) {
                         foundTr["id"] = tr["id"] ?? foundTr["id"]
                     }

src/Models/ThemeConfig/Conversion/PrepareTheme.ts

@@ -97,7 +97,7 @@ class SubstituteLayer extends Conversion<string | LayerConfigJson, LayerConfigJs
                     delete json["override"]["tagRenderings+"]
                 }
 
-                Utils.Merge(json["override"], found)
+                context.MergeObjectsForOverride(json["override"], found)
                 layers.push(found)
             } catch (e) {
                 context.err(
@@ -305,7 +305,7 @@ class ApplyOverrideAll extends DesugaringStep<LayoutConfigJson> {
         )
     }
 
-    convert(json: LayoutConfigJson, _: ConversionContext): LayoutConfigJson {
+    convert(json: LayoutConfigJson, ctx: ConversionContext): LayoutConfigJson {
         const overrideAll = json.overrideAll
         if (overrideAll === undefined) {
             return json
@@ -324,7 +324,7 @@ class ApplyOverrideAll extends DesugaringStep<LayoutConfigJson> {
 
         for (let layer of json.layers) {
             layer = Utils.Clone(<LayerConfigJson>layer)
-            Utils.Merge(overrideAll, layer)
+            ctx.MergeObjectsForOverride(overrideAll, layer)
             if (tagRenderingsPlus) {
                 if (!layer.tagRenderings) {
                     layer.tagRenderings = tagRenderingsPlus

src/Utils.ts

@@ -622,9 +622,6 @@ In the case that MapComplete is pointed to the testing grounds, the edit will be
         }
 
         for (const key in source) {
-            if (!source.hasOwnProperty(key)) {
-                continue
-            }
             if (key.startsWith("=")) {
                 const trimmedKey = key.substr(1)
                 target[trimmedKey] = source[key]