Fix bug: override preserves null's again

test/Models/ThemeConfig/Conversion/PrepareTheme.spec.ts

@@ -10,6 +10,7 @@ import LayerConfig from "../../../../Models/ThemeConfig/LayerConfig";
 import {ExtractImages} from "../../../../Models/ThemeConfig/Conversion/FixImages";
 import * as cyclofix from "../../../../assets/generated/themes/cyclofix.json"
 import {Tag} from "../../../../Logic/Tags/Tag";
+import {DesugaringContext} from "../../../../Models/ThemeConfig/Conversion/Conversion";
 
 
 const themeConfigJson: LayoutConfigJson = {
@@ -69,7 +70,6 @@ describe("PrepareTheme", () => {
 
     })
 
-
     it("should apply override", () => {
 
         const sharedLayers = new Map<string, LayerConfigJson>()
@@ -82,8 +82,65 @@ describe("PrepareTheme", () => {
         const layerUnderTest = <LayerConfig> themeConfig.layers.find(l => l.id === "public_bookcase")
         expect(layerUnderTest.source.geojsonSource).eq("https://example.com/data.geojson")
     })
-})
+    
+    it("should remove names which are overriden with null", () => {
+        const testLayer: LayerConfigJson = {
+            source: {
+                osmTags: "x=y"
+            },
+            id: "layer-example",
+            name: {
+                en: "Test layer - please ignore"
+            },
+            titleIcons : [],
+            mapRendering: null
+        }
+       const ctx: DesugaringContext =  {
+           sharedLayers: new Map<string, LayerConfigJson>([[
+               "layer-example", testLayer
+           ]]),
+           tagRenderings: new Map<string, TagRenderingConfigJson>()
 
+       }
+       const layout : LayoutConfigJson=
+           {
+               description: "A testing theme",
+               icon: "",
+               id: "",
+               layers: [
+                   "layer-example",
+                   {
+                       "builtin": "layer-example",
+                       "override": {
+                           "name": null,
+                           "minzoom": 18
+                       }
+                   }
+               ],
+               maintainer: "Me",
+               startLat: 0,
+               startLon: 0,
+               startZoom: 0,
+               title: "Test theme",
+               version: ""
+
+           }
+        const rewritten = new PrepareTheme(ctx, {
+            skipDefaultLayers: true
+        }).convertStrict(layout, "test")
+        expect(rewritten.layers[0]).deep.eq(testLayer)
+        expect(rewritten.layers[1]).deep.eq({
+            source: {
+                osmTags: "x=y"
+            },
+            id: "layer-example",
+            name:null,
+            minzoom: 18,
+            mapRendering: null,
+            titleIcons: []
+        })
+    })
+})
 
 describe("ExtractImages", () => {
     it("should find all images in a themefile", () => {