Fix #274. Add re-login button to error page.

webapp/i18n/en.json

@@ -161,6 +161,8 @@
   "ViewTitle.untitled-board": "Untitled board",
   "Workspace.editing-board-template": "You're editing a board template",
   "default-properties.title": "Title",
+  "error.no-workspace": "Your session may have expired or you may not have access to this workspace.",
+  "error.relogin": "Log in again",
   "login.log-in-button": "Log in",
   "login.log-in-title": "Log in",
   "login.register-button": "or create an account if you don't have one",

webapp/src/pages/errorPage.scss

@@ -29,7 +29,7 @@
     }
 
     > .Button {
-        margin-top: 10px;
+        margin-top: 30px;
         margin-bottom: 20px;
         min-height: 38px;
         min-width: 250px;

webapp/src/pages/errorPage.tsx

@@ -1,13 +1,35 @@
 // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
 // See LICENSE.txt for license information.
 import React from 'react'
+import {FormattedMessage} from 'react-intl'
 
+import octoClient from '../octoClient'
+import Button from '../widgets/buttons/button'
 import './errorPage.scss'
 
 const ErrorPage = React.memo(() => {
     return (
         <div className='ErrorPage'>
             <div className='title'>{'Error'}</div>
+            <div>
+                <FormattedMessage
+                    id='error.no-workspace'
+                    defaultMessage='Your session may have expired or you may not have access to this workspace.'
+                />
+            </div>
+            <br/>
+            <Button
+                filled={true}
+                onClick={() => {
+                    octoClient.logout()
+                    window.location.href = '/login'
+                }}
+            >
+                <FormattedMessage
+                    id='error.relogin'
+                    defaultMessage='Log in again'
+                />
+            </Button>
         </div>
     )
 })