Implement a better workaround for chrome-error:// URLs

It looks like chrome-error://chromewebdata/ triggers another invalid scheme
load which is why the endless loop happens. When we install a custom scheme
handler for chrome-error:// we can at least show an error page.

(cherry picked from commit b1506274c52f2ea84562407a72c3678868c180b3)

2 files changed, 10 insertions, 7 deletions

diff --git a/qutebrowser/browser/webengine/webenginequtescheme.py b/qutebrowser/browser/webengine/webenginequtescheme.py
index ac583a671..80269ba85 100644
--- a/qutebrowser/browser/webengine/webenginequtescheme.py
+++ b/qutebrowser/browser/webengine/webenginequtescheme.py
@@ -19,7 +19,7 @@
 
 """QtWebEngine specific qute://* handlers and glue code."""
 
-from PyQt5.QtCore import QBuffer, QIODevice
+from PyQt5.QtCore import QBuffer, QIODevice, QUrl
 from PyQt5.QtWebEngineCore import (QWebEngineUrlSchemeHandler,
                                    QWebEngineUrlRequestJob)
 
@@ -34,6 +34,9 @@ class QuteSchemeHandler(QWebEngineUrlSchemeHandler):
     def install(self, profile):
         """Install the handler for qute:// URLs on the given profile."""
         profile.installUrlSchemeHandler(b'qute', self)
+        if qtutils.version_check('5.11', compiled=False):
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-63378
+            profile.installUrlSchemeHandler(b'chrome-error', self)
 
     def requestStarted(self, job):
         """Handle a request for a qute: scheme.
@@ -45,6 +48,12 @@ class QuteSchemeHandler(QWebEngineUrlSchemeHandler):
             job: QWebEngineUrlRequestJob
         """
         url = job.requestUrl()
+
+        if url.scheme() == 'chrome-error':
+            # WORKAROUND for https://bugreports.qt.io/browse/QTBUG-63378
+            job.fail(QWebEngineUrlRequestJob.UrlInvalid)
+            return
+
         assert job.requestMethod() == b'GET'
         assert url.scheme() == 'qute'
         log.misc.debug("Got request for {}".format(url.toDisplayString()))
diff --git a/qutebrowser/browser/webengine/webenginetab.py b/qutebrowser/browser/webengine/webenginetab.py
index 5cc87091a..87fbb1fc7 100644
--- a/qutebrowser/browser/webengine/webenginetab.py
+++ b/qutebrowser/browser/webengine/webenginetab.py
@@ -1021,12 +1021,6 @@ 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(