Added feedback when unauthorized user attempts login

src/backends/github/AuthenticationPage.css

@@ -1,5 +1,6 @@
 .root {
   display: flex;
+  flex-flow: column nowrap;
   align-items: center;
   justify-content: center;
   height: 100vh;

src/backends/github/AuthenticationPage.js

@@ -1,12 +1,13 @@
 import React from 'react';
 import Button from 'react-toolbox/lib/button';
+import { Toast } from '../../components/UI';
 import Authenticator from '../../lib/netlify-auth';
 import { Icon } from '../../components/UI';
 import styles from './AuthenticationPage.css';
 
 export default class AuthenticationPage extends React.Component {
   static propTypes = {
-    onLogin: React.PropTypes.func.isRequired,
+    onLogin: React.PropTypes.func.isRequired
   };
 
   state = {};
@@ -16,7 +17,7 @@ export default class AuthenticationPage extends React.Component {
     const cfg = {
       base_url: this.props.base_url,
       site_id: (document.location.host.split(':')[0] === 'localhost') ? 'cms.netlify.com' : this.props.siteId
-    }
+    };
     const auth = new Authenticator(cfg);
 
     auth.authenticate({ provider: 'github', scope: 'repo' }, (err, data) => {
@@ -28,12 +29,19 @@ export default class AuthenticationPage extends React.Component {
     });
   };
 
+  handleError = message => (
+    <Toast kind="warning" message={message} />
+  );
+
   render() {
-    const { loginError } = this.state;
+    let { loginError } = this.state;
+    if (this.props.error !== null && this.props.error !== undefined) {
+      loginError = this.props.error;
+    }
 
     return (
       <section className={styles.root}>
-        {loginError && <p>{loginError}</p>}
+        {loginError && this.handleError(loginError.replace("Error: ", ""))}
         <Button
           className={styles.button}
           raised

src/backends/github/implementation.js

@@ -35,8 +35,7 @@ export default class GitHub {
       this.api.collaborator(user.login).then((status) => {
         if (status === 404 || status === 403) {
           // Unauthorized user
-          alert("Sorry, but you don't appear to have publisher access. If you think this is incorrect, talk to the site administrator");
-          throw new Error('Talk to the site administrator to get publishing access.');
+          throw new Error("Sorry, your user doesn't have CMS access. If you think this is incorrect, talk to the site administrator");
         } else if (status === 204) {
           // Authorized user
           user.token = state.token;