Add error handling on admin page (fixes #274)

public/js/admin.js

@@ -31,6 +31,9 @@ const component = () => {
 					this.scanMs = data.milliseconds;
 					this.scanTitles = data.titles;
 				})
+				.catch(e => {
+					alert('danger', `Failed to trigger a scan. Error: ${e}`);
+				})
 				.always(() => {
 					this.scanning = false;
 				});

src/views/admin.html.ecr

@@ -40,5 +40,6 @@
 <a class="uk-button uk-button-danger" href="<%= base_url %>logout">Log Out</a>
 
 <% content_for "script" do %>
+  <script src="<%= base_url %>js/alert.js"></script>
   <script src="<%= base_url %>js/admin.js"></script>
 <% end %>