fix: fix exception when QR code is disabled in configuration

Problem found in https://github.com/PrivateBin/PrivateBin/pull/2060

js/privatebin.js

@@ -4278,7 +4278,9 @@ window.PrivateBin = (function () {
             cloneButton.classList.remove('hidden');
             rawTextButton.classList.remove('hidden');
             downloadTextButton.classList.remove('hidden');
-            qrCodeLink.classList.remove('hidden');
+            if (qrCodeLink) {
+                qrCodeLink.classList.remove('hidden');
+            }
 
             viewButtonsDisplayed = true;
         };
@@ -4298,7 +4300,9 @@ window.PrivateBin = (function () {
             newButton.classList.add('hidden');
             rawTextButton.classList.add('hidden');
             downloadTextButton.classList.add('hidden');
-            qrCodeLink.classList.add('hidden');
+            if (qrCodeLink) {
+                qrCodeLink.classList.add('hidden');
+            }
             me.hideEmailButton();
 
             viewButtonsDisplayed = false;

js/test/TopNav.js

@@ -15,6 +15,27 @@ describe('TopNav', function () {
             cleanup();
         });
 
+        it(
+            'shows navigation elements when the QR code button is disabled',
+            function () {
+                document.documentElement.innerHTML =
+                    '<nav><button id="newbutton" class="hidden"></button>' +
+                    '<button id="clonebutton" class="hidden"></button>' +
+                    '<button id="rawtextbutton" class="hidden"></button>' +
+                    '<button id="downloadtextbutton" class="hidden"></button></nav>';
+                PrivateBin.TopNav.init();
+
+                assert.doesNotThrow(function () {
+                    PrivateBin.TopNav.showViewButtons();
+                });
+                assert.ok(!query('#newbutton').classList.contains('hidden'));
+                assert.ok(!query('#clonebutton').classList.contains('hidden'));
+                assert.ok(!query('#rawtextbutton').classList.contains('hidden'));
+                assert.ok(!query('#downloadtextbutton').classList.contains('hidden'));
+                cleanup();
+            }
+        );
+
         it(
             'displays & hides navigation elements for viewing an existing document',
             function () {

lib/Configuration.php

@@ -124,7 +124,7 @@ class Configuration
             'js/kjua-0.10.0.js'      => 'sha512-BYj4xggowR7QD150VLSTRlzH62YPfhpIM+b/1EUEr7RQpdWAGKulxWnOvjFx1FUlba4m6ihpNYuQab51H6XlYg==',
             'js/legacy.js'           => 'sha512-pRofxsrf5UItjiP22Dcjh3FAcBjF/n7h8U9/W5xqJk17U0N2U1oajhXypq/omo9jhwS1iVGOhWrRepoPeFns+w==',
             'js/prettify.js'         => 'sha512-puO0Ogy++IoA2Pb9IjSxV1n4+kQkKXYAEUtVzfZpQepyDPyXk8hokiYDS7ybMogYlyyEIwMLpZqVhCkARQWLMg==',
-            'js/privatebin.js'       => 'sha512-n3OsnBiq2RnihXpDKdwrRJrF55DHJLyiD7oZtA47WYhVE3o46rma/g9VZQdTH6dy44s0nPtthuPU0nu0mSaRZQ==',
+            'js/privatebin.js'       => 'sha512-3lZ1o/HpmT2f8OyfXMViF0MHbnM4nWkJQNHypHVGF16i+YrePEKr9fk0hkLk5m1CWyDjKr3xymARi6XmZQ4Z/A==',
             'js/purify-3.4.17.js'    => 'sha512-udF2zPdEyVCAxIGeBbeSGFK1Fj5c4eHGi6NqOSsr8M75lGs39POzgUNxO3SFxOg4cHfAoZJgR2EaXdmDi6v6AQ==',
             'js/showdown-2.1.0.js'   => 'sha512-WYXZgkTR0u/Y9SVIA4nTTOih0kXMEd8RRV6MLFdL6YU8ymhR528NLlYQt1nlJQbYz4EW+ZsS0fx1awhiQJme1Q==',
             'js/zlib-1.3.2.js'       => 'sha512-RAhJgxg9siMIA8ky4c10Rc2zUgnK80olHB8Tt1IOYWY4Eh1WmrviQkDn+sgBlb38ZHq3tzufGC41kP360gmosQ==',