fix(catalog-backend): fix stitcher error message and warn on unknown strategy mode

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Signed-off-by: Fredrik Adelöw <freben@gmail.com>

plugins/catalog-backend/src/stitching/DefaultStitcher.ts

@@ -80,7 +80,7 @@ export class DefaultStitcher {
 
   async start() {
     if (this.stopFunc) {
-      throw new Error('Processing engine is already started');
+      throw new Error('Stitcher is already started');
     }
 
     const { pollingInterval, stitchTimeout } = this.strategy;

plugins/catalog-backend/src/stitching/types.ts

@@ -42,6 +42,10 @@ export function stitchingStrategyFromConfig(
     options?.logger?.warn(
       "The 'immediate' stitching strategy mode has been removed and is no longer supported. Falling back to deferred stitching. Please remove the 'catalog.stitchingStrategy.mode' configuration key.",
     );
+  } else if (strategyMode !== undefined && strategyMode !== 'deferred') {
+    options?.logger?.warn(
+      `Unknown stitching strategy mode '${strategyMode}', falling back to deferred stitching. Please remove or correct the 'catalog.stitchingStrategy.mode' configuration key.`,
+    );
   }
 
   const pollingIntervalKey = 'catalog.stitchingStrategy.pollingInterval';