[bug] don't convert KbnServerErrors again (#106220)

* don't convert KbnServerErrors again

* Add test

* fixy fix

src/plugins/data/server/autocomplete/value_suggestions_route.ts

@@ -11,7 +11,7 @@ import { IRouter } from 'kibana/server';
 import { Observable } from 'rxjs';
 import { first } from 'rxjs/operators';
 import { getRequestAbortedSignal } from '../lib';
-import { getKbnServerError } from '../../../kibana_utils/server';
+import { getKbnServerError, reportServerError } from '../../../kibana_utils/server';
 import type { ConfigSchema } from '../../config';
 import { termsEnumSuggestions } from './terms_enum';
 import { termsAggSuggestions } from './terms_agg';
@@ -65,7 +65,8 @@ export function registerValueSuggestionsRoute(router: IRouter, config$: Observab
         );
         return response.ok({ body });
       } catch (e) {
-        throw getKbnServerError(e);
+        const kbnErr = getKbnServerError(e);
+        return reportServerError(response, kbnErr);
       }
     }
   );

src/plugins/kibana_utils/server/report_server_error.ts

@@ -24,6 +24,7 @@ export class KbnServerError extends KbnError {
  * @returns `KbnServerError`
  */
 export function getKbnServerError(e: Error) {
+  if (e instanceof KbnServerError) return e;
   return new KbnServerError(
     e.message ?? 'Unknown error',
     e instanceof ResponseError ? e.statusCode : 500,

test/api_integration/apis/suggestions/suggestions.js

@@ -44,5 +44,14 @@ export default function ({ getService }) {
           query: 'nes',
         })
         .expect(200, ['nestedValue']));
+
+    it('should return 404 if index is not found', () =>
+      supertest
+        .post('/api/kibana/suggestions/values/not_found')
+        .send({
+          field: 'baz.keyword',
+          query: '1',
+        })
+        .expect(404));
   });
 }