Reset newly set date when the work package is erroneous

frontend/app/components/work-packages/work-package-cache.service.ts

@@ -86,14 +86,19 @@ export class WorkPackageCacheService {
       return this.$q.when(workPackage);
     }
 
-    return workPackage.save()
+    const deferred = this.$q.defer();
+    workPackage.save()
       .then(() => {
         this.wpNotificationsService.showSave(workPackage);
         this.$rootScope.$emit('workPackagesRefreshInBackground');
+        deferred.resolve(workPackage);
       })
       .catch((error) => {
         this.wpNotificationsService.handleErrorResponse(error, workPackage);
+        deferred.reject(error);
       });
+
+    return deferred.promise;
   }
 
   loadWorkPackage(workPackageId: number, forceUpdate = false): State<WorkPackageResource> {

frontend/app/components/wp-table/timeline/cell-renderer/timeline-cell-renderer.ts

@@ -33,7 +33,7 @@ export class TimelineCellRenderer {
   /**
    * Restore the original date, if any was set.
    */
-  public onCancel(wp:WorkPackageResourceInterface, dates:CellDateMovement) {
+  public onCancel(wp:WorkPackageResourceInterface) {
     wp.restoreFromPristine('startDate');
     wp.restoreFromPristine('dueDate');
   }

frontend/app/components/wp-table/timeline/cell-renderer/timeline-milestone-cell-renderer.ts

@@ -28,7 +28,7 @@ export class TimelineMilestoneCellRenderer extends TimelineCellRenderer {
   /**
    * Restore the original date, if any was set.
    */
-  public onCancel(wp: WorkPackageResourceInterface, dates:CellMilestoneMovement) {
+  public onCancel(wp: WorkPackageResourceInterface) {
     wp.restoreFromPristine('date');
   }
 

frontend/app/components/wp-table/timeline/wp-timeline-cell-mouse-handler.ts

@@ -106,13 +106,6 @@ export function registerWorkPackageMouseHandler(this: void,
       return;
     }
 
-    if (cancelled) {
-      renderer.onCancel(renderInfo.workPackage, dateStates);
-    } else {
-      // Persist the changes
-      wpCacheService.saveIfChanged(renderInfo.workPackage);
-    }
-
     jBody.off("mousemove", mouseMoveFn);
     jBody.off("keyup", keyPressFn);
     jQuery(".hascontextmenu").css("cursor", "context-menu");
@@ -123,9 +116,20 @@ export function registerWorkPackageMouseHandler(this: void,
     startX = null;
     dateStates = {};
 
-    workPackageTimeline.refreshView();
-
+    if (cancelled) {
+      renderer.onCancel(renderInfo.workPackage);
+      return workPackageTimeline.refreshView();
     }
 
+    // Persist the changes
+    wpCacheService.saveIfChanged(renderInfo.workPackage)
+      .catch(() => {
+        // Reset the changes on error
+        renderer.onCancel(renderInfo.workPackage);
+      })
+      .finally(() => {
+        workPackageTimeline.refreshView();
+      });
+  }
 }