Make the action 'get-catalog-entity' throw ConflictError instead of Error

Signed-off-by: Gustaf Räntilä <g.rantila@gmail.com>

.changeset/curvy-sites-rhyme.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend': patch
+---
+
+The 'get-catalog-entity' action now throws a ConflictError instead of generic Error if multiple entities are found, so MCP call doesn't fail with 500.

plugins/catalog-backend/src/actions/createGetCatalogEntityAction.ts

@@ -15,7 +15,7 @@
  */
 import { ActionsRegistryService } from '@backstage/backend-plugin-api/alpha';
 import { stringifyEntityRef } from '@backstage/catalog-model';
-import { InputError } from '@backstage/errors';
+import { ConflictError, InputError } from '@backstage/errors';
 import { CatalogService } from '@backstage/plugin-catalog-node';
 
 export const createGetCatalogEntityAction = ({
@@ -76,7 +76,7 @@ Each entity is identified by a unique entity reference, which is a string of the
       }
 
       if (items.length > 1) {
-        throw new Error(
+        throw new ConflictError(
           `Multiple entities found with name "${
             input.name
           }", please provide more specific filters. Entities found: ${items