Try different workaround for test_ipc issues.

qutebrowser/misc/ipc.py

@@ -140,6 +140,10 @@ class IPCServer(QObject):
     @pyqtSlot(int)
     def on_error(self, err):
         """Convenience method which calls _socket_error on an error."""
+        if self._socket is None:
+            # Sometimes this gets called from stale sockets, especially in
+            # tests.
+            return
         self._timer.stop()
         log.ipc.debug("Socket error {}: {}".format(
             self._socket.error(), self._socket.errorString()))

tests/unit/misc/test_ipc.py

@@ -59,15 +59,13 @@ def qlocalserver(qapp):
 
 
 @pytest.yield_fixture
-def qlocalsocket(qapp, qtbot):
+def qlocalsocket(qapp):
     socket = QLocalSocket()
     yield socket
     socket.disconnectFromServer()
     if socket.state() != QLocalSocket.UnconnectedState:
         disconnected = socket.waitForDisconnected(100)
         assert disconnected
-    with qtbot.waitSignal(socket.destroyed, raising=False):
-        socket.deleteLater()
 
 
 class FakeSocket(QObject):