Chore: improve documentation and error messages

src/Models/ThemeConfig/Conversion/Conversion.ts

@@ -151,7 +151,11 @@ export class Each<X, Y> extends Conversion<X[], Y[]> {
                     values[i]?.["id"] !== undefined ? values[i]?.["id"] : ""
                 )
             }
-            const r = step.convert(values[i], c.enter(i))
+            let id = ""
+            if (values[i]?.["id"]) {
+                id = `(${values[i]?.["id"]})`
+            }
+            const r = step.convert(values[i], c.enter(i + id))
             result.push(r)
         }
         return result

src/Models/ThemeConfig/Json/UnitConfigJson.ts

@@ -1,5 +1,5 @@
 /**
- * In some cases, a value is represented in a certain unit (such as meters for heigt/distance/..., km/h for speed, ...)
+ * In some cases, a value is represented in a certain unit (such as meters for height/distance/..., km/h for speed, ...)
  *
  * Sometimes, multiple denominations are possible (e.g. km/h vs mile/h; megawatt vs kilowatt vs gigawatt for power generators, ...)
  *
@@ -14,9 +14,9 @@
  *
  * # Usage
  *
- * First of all, you define which keys have units applied, for example:
+ * First of all, you define which keys have units applied. This can be done centrally in the layer:
  *
- * ```
+ * ```json
  * units: [
  *  appliesTo: ["maxspeed", "maxspeed:hgv", "maxspeed:bus"]
  *  applicableUnits: [

src/Models/ThemeConfig/TagRenderingConfig.ts

@@ -197,7 +197,7 @@ export default class TagRenderingConfig {
                     json.freeform.key,
                     <any>Validators.availableTypes,
                     (s) => <any>s
-                )}`
+                )}. See https://source.mapcomplete.org/MapComplete/MapComplete/src/branch/develop/Docs/SpecialInputElements.md for more information`
             }
             const type: ValidatorType = <any>json.freeform.type ?? "string"