fix(prometheus): fixed bug in prometheus query editor, fixes #5107

public/app/plugins/datasource/prometheus/query_ctrl.ts

@@ -58,6 +58,10 @@ class PrometheusQueryCtrl extends QueryCtrl {
 
   updateLink() {
     var range = this.panelCtrl.range;
+    if (!range) {
+      return;
+    }
+
     var rangeDiff = Math.ceil((range.to.valueOf() - range.from.valueOf()) / 1000);
     var endTime = range.to.utc().format('YYYY-MM-DD HH:mm');
     var expr = {