Raise error on bad parameter

IPython/extensions/autoreload.py

@@ -566,6 +566,8 b' class AutoreloadMagics(Magics):'
             self._reloader.check_all = True
             self._reloader.enabled = True
             self._reloader.autoload_obj = True
+        else:
+            raise ValueError(f'Unrecognized parameter "{parameter_s}".')
 
     @line_magic
     def aimport(self, parameter_s="", stream=None):