Chore: small cleanups, formatting

src/Models/ThemeConfig/Conversion/Conversion.ts

@@ -32,7 +32,7 @@ export abstract class Conversion<TIn, TOut> {
         this.name = name
     }
 
-    public convertStrict(json: TIn, context?: ConversionContext): TOut {
+    public convertStrict(json: NonNullable<TIn>, context?: ConversionContext): TOut {
         context ??= ConversionContext.construct([], [])
         context = context.inOperation(this.name)
 
@@ -276,7 +276,7 @@ export class Fuse<T> extends DesugaringStep<T> {
                 "This fused pipeline of the following steps: " +
                 steps.map((s) => s.name).join(", "),
             Utils.Dedup([].concat(...steps.map((step) => step.modifiedAttributes))),
-            "Fuse(" + steps.map((s) => s.name).join(", ") + ")"
+            "Fuse"
         )
         this.steps = Utils.NoNull(steps)
     }

src/Models/ThemeConfig/Conversion/PrepareLayer.ts

@@ -1000,4 +1000,11 @@ export class PrepareLayer extends Fuse<LayerConfigJson> {
             new PruneFilters()
         )
     }
+
+    convert(json: LayerConfigJson, context: ConversionContext): LayerConfigJson {
+        if(json === undefined || json === null){
+            throw "Error: prepareLayer got null"
+        }
+        return super.convert(json, context)
+    }
 }

src/Models/ThemeConfig/Conversion/PrepareTheme.ts

@@ -472,7 +472,7 @@ class PreparePersonalTheme extends DesugaringStep<ThemeConfigJson> {
 class WarnForUnsubstitutedLayersInTheme extends DesugaringStep<ThemeConfigJson> {
     constructor() {
         super(
-            "Generates a warning if a theme uses an unsubstituted layer",
+            "Generates a warning if a theme uses an inline layer; we recommend splitting of all layers in separate files",
             ["layers"],
             "WarnForUnsubstitutedLayersInTheme"
         )