Add more and unify tests for absent object cases

- Unify test data for nonexistence of an object/string and collection.
- Introduce more test through adding missing test data to existing tests.
- Improve logic for checking absence of values to match tests.
- Add missing tests for absent value validation.
- Update documentation to include shared test functionality.

src/application/Common/ScriptingLanguage/ScriptingLanguageFactory.ts

@@ -20,7 +20,7 @@ export abstract class ScriptingLanguageFactory<T> implements IScriptingLanguageF
   protected registerGetter(language: ScriptingLanguage, getter: Getter<T>) {
     assertInRange(language, ScriptingLanguage);
     if (!getter) {
-      throw new Error('undefined getter');
+      throw new Error('missing getter');
     }
     if (this.getters.has(language)) {
       throw new Error(`${ScriptingLanguage[language]} is already registered`);