bug: impossible to unload plugin if there was error on previous attempt of unloading

[em92]

(04:03:58) [DEBUG @ minqlx.dispatch] client_command(Player(5:'posT':76561198277142780), 'score')
(04:03:58) [DEBUG @ minqlx.dispatch] client_command(Player(6:'«tdog»▒~D▒':76561198244154338), 'score')
(04:03:58) [DEBUG @ minqlx.dispatch] client_command(Player(13:'lwf':76561198154317273), 'say !load essentials')
(04:03:58) [DEBUG @ minqlx.plugin_manager.execute] 76561198154317273 executed: load @ plugin_manager -> chat
(04:03:58) [INFO @ minqlx.load_plugin] Loading plugin 'essentials'...
(04:03:58) [INFO @ minqlx.unload_plugin] Unloading plugin 'essentials'...
(04:03:58) [DEBUG @ minqlx.dispatch] unload('essentials',)
(04:03:58) [ERROR @ minqlx.essentials.log_exception] Traceback (most recent call last):
(04:03:58) [ERROR @ minqlx.essentials.log_exception]   File "minqlx.zip/minqlx/_core.py", line 382, in unload_plugin
(04:03:58) [ERROR @ minqlx.essentials.log_exception]     plugins[plugin].remove_command(cmd.name, cmd.handler)
(04:03:58) [ERROR @ minqlx.essentials.log_exception]   File "minqlx.zip/minqlx/_plugin.py", line 138, in remove_command
(04:03:58) [ERROR @ minqlx.essentials.log_exception]     minqlx.COMMANDS.remove_command(cmd)
(04:03:58) [ERROR @ minqlx.essentials.log_exception]   File "minqlx.zip/minqlx/_commands.py", line 134, in remove_command
(04:03:58) [ERROR @ minqlx.essentials.log_exception]     raise ValueError("Attempted to remove a command that was never added.")
(04:03:58) [ERROR @ minqlx.essentials.log_exception] ValueError: Attempted to remove a command that was never added.
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception] Traceback (most recent call last):
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "./minqlx-plugins/plugin_manager.py", line 35, in cmd_load
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     minqlx.load_plugin(msg[1])
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "minqlx.zip/minqlx/_core.py", line 349, in load_plugin
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     return reload_plugin(plugin)
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "minqlx.zip/minqlx/_core.py", line 393, in reload_plugin
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     unload_plugin(plugin)
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "minqlx.zip/minqlx/_core.py", line 382, in unload_plugin
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     plugins[plugin].remove_command(cmd.name, cmd.handler)
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "minqlx.zip/minqlx/_plugin.py", line 138, in remove_command
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     minqlx.COMMANDS.remove_command(cmd)
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]   File "minqlx.zip/minqlx/_commands.py", line 134, in remove_command
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception]     raise ValueError("Attempted to remove a command that was never added.")
(04:03:58) [ERROR @ minqlx.plugin_manager.log_exception] ValueError: Attempted to remove a command that was never added.
(04:03:58) [DEBUG @ minqlx.dispatch] chat(Player(13:'lwf':76561198154317273), '!load essentials', chat)
(04:03:58) [DEBUG @ minqlx.handle_console_print] lwf^7^Y: !load essentials
(04:03:59) [DEBUG @ minqlx.handle_console_print] broadcast: print "Plugin ^6essentials ^7has failed to load: ValueError - Attempted to remove a command that was never\nadded.\n"\n\n

Reported by @lonewulfa on https://gist.github.com/lonewulfa/d7d94c539439b241c76d39794f196f5e