Better error for invalid argument count

qutebrowser/commands/command.py

@@ -81,7 +81,9 @@ class Command(QObject):
             pass
         else:
             raise ArgumentCountError("{}-{} args expected, but got {}".format(
-                self.nargs[0], self.nargs[1], len(args)))
+                self.nargs[0],
+                self.nargs[1] if self.nargs[1] is not None else 'inf',
+                len(args)))
 
     def run(self, args=None, count=None):
         """Run the command.

qutebrowser/commands/parsers.py

@@ -208,10 +208,10 @@ class CommandParser:
         try:
             self.parse(text)
             self._check()
-        except ArgumentCountError:
+        except ArgumentCountError as e:
             if ignore_exc:
-                message.error("{}: invalid argument count".format(
-                    self._cmd.name))
+                message.error("{}: invalid argument count - {}".format(
+                    self._cmd.name, str(e)))
                 return False
             else:
                 raise