feat: throw error if extensions point tries to set data parser multiple times

Signed-off-by: secustor <sebastian@poxhofer.at>

plugins/catalog-backend/src/service/CatalogPlugin.ts

@@ -42,7 +42,7 @@ class CatalogProcessingExtensionPointImpl
   #processors = new Array<CatalogProcessor>();
   #entityProviders = new Array<EntityProvider>();
   #placeholderResolvers: Record<string, PlaceholderResolver> = {};
-  entityDataParser: CatalogProcessorParser = defaultEntityDataParser;
+  entityDataParser?: CatalogProcessorParser;
 
   addProcessor(
     ...processors: Array<CatalogProcessor | Array<CatalogProcessor>>
@@ -65,6 +65,11 @@ class CatalogProcessingExtensionPointImpl
   }
 
   setEntityDataParser(parser: CatalogProcessorParser): void {
+    if (this.entityDataParser) {
+      throw new Error(
+        'Attempted to install second EntityDataParser. Only one can be set.',
+      );
+    }
     this.entityDataParser = parser;
   }
 
@@ -171,7 +176,9 @@ export const catalogPlugin = createBackendPlugin({
         });
         builder.addProcessor(...processingExtensions.processors);
         builder.addEntityProvider(...processingExtensions.entityProviders);
-        builder.setEntityDataParser(processingExtensions.entityDataParser);
+        builder.setEntityDataParser(
+          processingExtensions.entityDataParser ?? defaultEntityDataParser,
+        );
 
         Object.entries(processingExtensions.placeholderResolvers).forEach(
           ([key, resolver]) => builder.setPlaceholderResolver(key, resolver),