Loki: Fix error handling (#26291)

* Loki: Fix error handling

* Keep custom error processing for escaping

* Fix failing test

Co-authored-by: Ivana <ivana.huckova@gmail.com>

public/app/plugins/datasource/loki/datasource.test.ts

@@ -176,7 +176,9 @@ describe('LokiDatasource', () => {
       datasourceRequestMock.mockImplementation(
         jest.fn().mockReturnValueOnce(
           Promise.reject({
-            data: 'parse error at line 1, col 6: invalid char escape',
+            data: {
+              message: 'parse error at line 1, col 6: invalid char escape',
+            },
             status: 400,
             statusText: 'Bad Request',
           })
@@ -189,7 +191,7 @@ describe('LokiDatasource', () => {
       try {
         await ds.query(options).toPromise();
       } catch (err) {
-        expect(err.message).toBe(
+        expect(err.data.message).toBe(
           'Error: parse error at line 1, col 6: invalid char escape. Make sure that all special characters are escaped with \\. For more information on escaping of special characters visit LogQL documentation at https://github.com/grafana/loki/blob/master/docs/logql.md.'
         );
       }

public/app/plugins/datasource/loki/datasource.ts

 // Libraries
-import { isEmpty, map as lodashMap } from 'lodash';
+import { isEmpty, map as lodashMap, cloneDeep } from 'lodash';
 import { Observable, from, merge, of } from 'rxjs';
-import { map, filter, catchError, switchMap } from 'rxjs/operators';
+import { map, catchError, switchMap } from 'rxjs/operators';
 
 // Services & Utils
 import { DataFrame, dateMath, FieldCache, QueryResultMeta } from '@grafana/data';
-import { getBackendSrv, BackendSrvRequest } from '@grafana/runtime';
+import { getBackendSrv, BackendSrvRequest, FetchError } from '@grafana/runtime';
 import { addLabelToQuery } from 'app/plugins/datasource/prometheus/add_label_to_query';
 import { TemplateSrv } from 'app/features/templating/template_srv';
-import { safeStringifyValue, convertToWebSocketUrl } from 'app/core/utils/explore';
+import { convertToWebSocketUrl } from 'app/core/utils/explore';
 import { lokiResultsToTableModel, processRangeQueryResponse, lokiStreamResultToDataFrame } from './result_transformer';
 import { getHighlighterExpressionsFromQuery } from './query_utils';
 
@@ -120,8 +120,6 @@ export class LokiDatasource extends DataSourceApi<LokiQuery, LokiOptions> {
     };
 
     return this._request(INSTANT_QUERY_ENDPOINT, query).pipe(
-      catchError((err: any) => this.throwUnless(err, err.cancelled, target)),
-      filter((response: any) => (response.cancelled ? false : true)),
       map((response: { data: LokiResponse }) => {
         if (response.data.data.resultType === LokiResultType.Stream) {
           return {
@@ -200,8 +198,7 @@ export class LokiDatasource extends DataSourceApi<LokiQuery, LokiOptions> {
     }
     const query = this.createRangeQuery(target, queryOptions);
     return this._request(RANGE_QUERY_ENDPOINT, query).pipe(
-      catchError((err: any) => this.throwUnless(err, err.cancelled || err.status === 404, target)),
-      filter((response: any) => (response.cancelled ? false : true)),
+      catchError((err: any) => this.throwUnless(err, err.status === 404, target)),
       switchMap((response: { data: LokiResponse; status: number }) =>
         processRangeQueryResponse(
           response.data,
@@ -498,42 +495,22 @@ export class LokiDatasource extends DataSourceApi<LokiQuery, LokiOptions> {
     return (row && row.searchWords && row.searchWords.length > 0) === true;
   }
 
-  throwUnless = (err: any, condition: boolean, target: LokiQuery) => {
+  throwUnless(err: FetchError, condition: boolean, target: LokiQuery) {
     if (condition) {
       return of(err);
     }
 
-    const error: DataQueryError = this.processError(err, target);
+    const error = this.processError(err, target);
     throw error;
-  };
-
-  processError = (err: any, target: LokiQuery): DataQueryError => {
-    const error: DataQueryError = {
-      message: (err && err.statusText) || 'Unknown error during query transaction. Please check JS console logs.',
-      refId: target.refId,
-    };
+  }
 
-    if (err.data) {
-      if (typeof err.data === 'string') {
-        if (err.data.includes('escape') && target.expr.includes('\\')) {
-          error.message = `Error: ${err.data}. Make sure that all special characters are escaped with \\. For more information on escaping of special characters visit LogQL documentation at https://github.com/grafana/loki/blob/master/docs/logql.md.`;
-        } else {
-          error.message = err.data;
-        }
-      } else if (err.data.error) {
-        error.message = safeStringifyValue(err.data.error);
-      }
-    } else if (err.message) {
-      error.message = err.message;
-    } else if (typeof err === 'string') {
-      error.message = err;
+  processError(err: FetchError, target: LokiQuery) {
+    let error = cloneDeep(err);
+    if (err.data.message.includes('escape') && target.expr.includes('\\')) {
+      error.data.message = `Error: ${err.data.message}. Make sure that all special characters are escaped with \\. For more information on escaping of special characters visit LogQL documentation at https://github.com/grafana/loki/blob/master/docs/logql.md.`;
     }
-
-    error.status = err.status;
-    error.statusText = err.statusText;
-
     return error;
-  };
+  }
 
   adjustInterval(interval: number, range: number) {
     // Loki will drop queries that might return more than 11000 data points.