Fix issue board transient failure

app/assets/javascripts/boards/components/board_new_issue.js

@@ -68,7 +68,7 @@ export default {
         <div class="flash-container"
           v-if="error">
           <div class="flash-alert">
-            An error occured. Please try again.
+            An error occurred. Please try again.
           </div>
         </div>
         <label class="label-light"

app/assets/javascripts/boards/components/modal/index.js

 /* global ListIssue */
+/* global Flash */
 
 import Vue from 'vue';
 import queryData from '../../utils/query_data';
@@ -108,7 +109,7 @@ gl.issueBoards.IssuesModal = Vue.extend({
         if (!this.issuesCount) {
           this.issuesCount = data.size;
         }
-      });
+      }).catch(() => new Flash('An unexpected error has occurred.', 'alert'));
     },
   },
   computed: {

app/assets/javascripts/boards/models/list.js

 /* eslint-disable space-before-function-paren, no-underscore-dangle, class-methods-use-this, consistent-return, no-shadow, no-param-reassign, max-len, no-unused-vars */
 /* global ListIssue */
 /* global ListLabel */
+/* global Flash */
 import queryData from '../utils/query_data';
 
 const PER_PAGE = 20;
@@ -44,7 +45,8 @@ class List {
         this.position = data.position;
 
         return this.getIssues();
-      });
+      })
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   destroy () {
@@ -52,11 +54,13 @@ class List {
     gl.issueBoards.BoardsStore.state.lists.splice(index, 1);
     gl.issueBoards.BoardsStore.updateNewListDropdown(this.id);
 
-    gl.boardService.destroyList(this.id);
+    gl.boardService.destroyList(this.id)
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   update () {
-    gl.boardService.updateList(this.id, this.position);
+    gl.boardService.updateList(this.id, this.position)
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   nextPage () {
@@ -91,7 +95,8 @@ class List {
         }
 
         this.createIssues(data.issues);
-      });
+      })
+      .catch(() => new Flash('Failed to load issues, please try again.', 'alert'));
   }
 
   newIssue (issue) {
@@ -103,7 +108,8 @@ class List {
         const data = resp.json();
         issue.id = data.iid;
         issue.milestone = data.milestone;
-      });
+      })
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   createIssues (data) {
@@ -147,11 +153,13 @@ class List {
     this.issues.splice(oldIndex, 1);
     this.issues.splice(newIndex, 0, issue);
 
-    gl.boardService.moveIssue(issue.id, null, null, moveBeforeIid, moveAfterIid);
+    gl.boardService.moveIssue(issue.id, null, null, moveBeforeIid, moveAfterIid)
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   updateIssueLabel(issue, listFrom, moveBeforeIid, moveAfterIid) {
-    gl.boardService.moveIssue(issue.id, listFrom.id, this.id, moveBeforeIid, moveAfterIid);
+    gl.boardService.moveIssue(issue.id, listFrom.id, this.id, moveBeforeIid, moveAfterIid)
+      .catch(() => new Flash('An unexpected error has occurred.', 'alert'));
   }
 
   findIssue (id) {