Chore: Fix issues found by staticcheck (#28802)

* Fix linting issues

Signed-off-by: Arve Knudsen <arve.knudsen@gmail.com>

pkg/tsdb/mysql/macros.go

@@ -35,7 +35,7 @@ func (m *mySqlMacroEngine) Interpolate(query *tsdb.Query, timeRange *tsdb.TimeRa
 	matches := restrictedRegExp.FindAllStringSubmatch(sql, 1)
 	if len(matches) > 0 {
 		m.logger.Error("show grants, session_user(), current_user(), system_user() or user() not allowed in query")
-		return "", errors.New("Invalid query. Inspect Grafana server log for details")
+		return "", errors.New("invalid query - inspect Grafana server log for details")
 	}
 
 	rExp, _ := regexp.Compile(sExpr)
@@ -135,6 +135,6 @@ func (m *mySqlMacroEngine) evaluateMacro(name string, args []string) (string, er
 		}
 		return "", err
 	default:
-		return "", fmt.Errorf("Unknown macro %v", name)
+		return "", fmt.Errorf("unknown macro %v", name)
 	}
 }

pkg/tsdb/mysql/macros_test.go

@@ -181,7 +181,7 @@ func TestMacroEngine(t *testing.T) {
 
 			for _, tc := range tcs {
 				_, err := engine.Interpolate(nil, nil, tc)
-				So(err.Error(), ShouldEqual, "Invalid query. Inspect Grafana server log for details")
+				So(err.Error(), ShouldEqual, "invalid query - inspect Grafana server log for details")
 			}
 		})
 	})

pkg/tsdb/mysql/mysql.go

@@ -150,4 +150,4 @@ func (t *mysqlQueryResultTransformer) TransformQueryError(err error) error {
 	return err
 }
 
-var errQueryFailed = errors.New("Query failed. Please inspect Grafana server log for details")
+var errQueryFailed = errors.New("query failed - please inspect Grafana server log for details")