"No connection" message on timeout #370 (#381)

* check status

* move check

* rename

src/panel/graph_panel/services/analytic_service.ts

@@ -280,7 +280,11 @@ export class AnalyticService {
       // xhrStatus may be one of: ('complete', 'error', 'timeout' or 'abort')
       // See: https://github.com/angular/angular.js/blob/55075b840c9194b8524627a293d6166528b9a1c2/src/ng/http.js#L919-L920
       if(error.xhrStatus !== 'complete' || error.status > 500) {
-        this.displayConnectionErrorAlert();
+        if(error.status === 504) {
+          this.displayConnectionTimeoutAlert();
+        } else {
+          this.displayNoConnectionAlert();
+        }
         this._isUp = false;
         throw new Error(`Fetching error: ${error.status}: ${error.statusText}`);
       } else {
@@ -323,7 +327,15 @@ export class AnalyticService {
     return this._analyticRequest('DELETE', url, data);
   }
 
-  private displayConnectionErrorAlert() {
+  private displayNoConnectionAlert() {
+    const message = [
+      'No connection to Hastic Server',
+      `Hastic Datasource URL: "${this._hasticDatasourceURL}"`,
+    ]
+    this._displayConnectionAlert(HasticDatasourceStatus.NOT_AVAILABLE, message);
+  }
+
+  private displayConnectionTimeoutAlert() {
     const message = [
       'Timeout when connecting to Hastic Server',
       `Hastic Datasource URL: "${this._hasticDatasourceURL}"`,