Merge branch 'feature/parent_selector' into dev

frontend/src/routes/task/ParentSelector.svelte

@@ -21,7 +21,10 @@
 </script>
 
 <div class="overlay parent_selector">
-	<h2>{t('select a new parent for {entity}',{entity:task.name})}</h2>
+	<h2>
+		{t('select a new parent for {entity}',{entity:task.name})}
+		<button onclick={ev => select(null)}>{t('abort')}</button>
+	</h2>
 	{t('project')}: {project.name}
 	<TaskTree {tree} {select} />
 </div>

frontend/src/routes/task/View.svelte

@@ -193,7 +193,7 @@
 
     function update_parent(newVal){
         select_parent = false;
-        update({parent_task_id:newVal.id});
+        if (newVal) update({parent_task_id:newVal.id});
     }
 
     function updatePermission(user_id,permission){