Add Error 401 page when unauthorized

src/views/errors.js

+const m = require('mithril');
+
+export class Error401 {
+  static view() {
+    return m('div', 'This page is only accessible for authenticated users. Please log in.');
+  }
+}
+
+export class Error404 {
+  static view() {
+    return m('div', 'This page does not exist.');
+  }
+}

src/views/studydocList.js

 import * as studydocs from '../models/studydocs';
 import { apiUrl } from '../models/config';
+import { isLoggedIn } from '../models/auth';
+import { Error401 } from './errors';
 
 const m = require('mithril');
 
@@ -18,6 +20,8 @@ export default class studydocList {
   }
 
   static view() {
+    if (!isLoggedIn()) return m(Error401);
+
     return m('div', [
       m('form', {
         onsubmit: (e) => {

src/views/studydocNew.js

 // import Ajv from 'ajv';
 import * as studydocs from '../models/studydocs';
 // import { apiUrl } from '../models/config';
+import { isLoggedIn } from '../models/auth';
 import { log } from '../models/log';
+import { Error401 } from './errors';
 
 const m = require('mithril');
 
@@ -25,6 +27,8 @@ export default class studydocNew {
   }
 
   view() {
+    if (!isLoggedIn()) return m(Error401);
+
     return m('div', [
       m('form', {
         onsubmit: (e) => {