Clean up :later timers correctly on exceptions.

qutebrowser/utils/utilcmds.py

@@ -37,22 +37,26 @@ def later(ms: int, *command, win_id):
         ms: How many milliseconds to wait.
         *command: The command to run, with optional args.
     """
-    app = objreg.get('app')
-    timer = usertypes.Timer(name='later', parent=app)
-    timer.setSingleShot(True)
     if ms < 0:
         raise cmdexc.CommandError("I can't run something in the past!")
+    cmdline = ' '.join(command)
+    commandrunner = runners.CommandRunner(win_id)
+    app = objreg.get('app')
+    timer = usertypes.Timer(name='later', parent=app)
+    try:
+        timer.setSingleShot(True)
         try:
             timer.setInterval(ms)
         except OverflowError:
-        raise cmdexc.CommandError("Numeric argument is too large for internal "
-                                  "int representation.")
-    cmdline = ' '.join(command)
-    commandrunner = runners.CommandRunner(win_id)
+            raise cmdexc.CommandError("Numeric argument is too large for "
+                                      "internal int representation.")
         timer.timeout.connect(
             functools.partial(commandrunner.run_safely, cmdline))
         timer.timeout.connect(timer.deleteLater)
         timer.start()
+    except:  # pylint: disable=bare-except
+        timer.deleteLater()
+        raise
 
 
 @cmdutils.register(scope='window')