Add a workaround for chrome-error:// loops on Qt 5.11

See #3661

qutebrowser/browser/webengine/webenginetab.py

@@ -1030,6 +1030,12 @@ class WebEngineTab(browsertab.AbstractTab):
         if not ok and not js_enabled:
             self.dump_async(self._error_page_workaround)
 
+        if (not ok and
+                self.url() == QUrl('chrome-error://chromewebdata/') and
+                qtutils.version_check('5.11', compiled=False)):
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-63378
+            self._show_error_page(QUrl(), "Unknown URL scheme")
+
         if ok and self._reload_url is not None:
             # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-66656
             log.config.debug(

qutebrowser/html/error.html

@@ -74,7 +74,7 @@ function tryagain()
 			</td>
 			<td style="padding-left: 40px;">
 				<h1>Unable to load page</h1>
-				Error while opening {{ url }}<br>
+				Error while opening {{ url | default('page', true) }}<br>
 				<p id="error-message-text" style="color: #a31a1a;">{{ error }}</p><br><br>
 
 				<form name="bl">