Loki: Run logs volume for query when switching from trace to logs (#72268)

Loki: Run logs volume for query that has no queryType (defaults to range)

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

@@ -1093,6 +1093,24 @@ describe('LokiDatasource', () => {
     });
 
     describe('logs volume', () => {
+      // The default queryType value is Range
+      it('returns logs volume for query with no queryType', () => {
+        expect(
+          ds.getSupplementaryQuery(
+            { type: SupplementaryQueryType.LogsVolume },
+            {
+              expr: '{label=value}',
+              refId: 'A',
+            }
+          )
+        ).toEqual({
+          expr: 'sum by (level) (count_over_time({label=value}[$__interval]))',
+          queryType: LokiQueryType.Range,
+          refId: 'log-volume-A',
+          supportingQueryType: SupportingQueryType.LogsVolume,
+        });
+      });
+
       it('returns logs volume query for range log query', () => {
         expect(
           ds.getSupplementaryQuery(

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

@@ -194,7 +194,7 @@ export class LokiDatasource
     switch (options.type) {
       case SupplementaryQueryType.LogsVolume:
         // it has to be a logs-producing range-query
-        isQuerySuitable = !!(query.expr && isLogsQuery(query.expr) && query.queryType === LokiQueryType.Range);
+        isQuerySuitable = !!(expr && isLogsQuery(expr) && normalizedQuery.queryType === LokiQueryType.Range);
         if (!isQuerySuitable) {
           return undefined;
         }
@@ -209,7 +209,7 @@ export class LokiDatasource
 
       case SupplementaryQueryType.LogsSample:
         // it has to be a metric query
-        isQuerySuitable = !!(query.expr && !isLogsQuery(query.expr));
+        isQuerySuitable = !!(expr && !isLogsQuery(expr));
         if (!isQuerySuitable) {
           return undefined;
         }