Add guild settings getter in command events

[Matyrobbrt]

Pull Request

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• My PR fixes a bug, error, or other issue with the library's codebase.
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Description

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This PR adds 2 utility methods in the command and interaction events for getting the settings of the guild, using the class of the settings. Those methods will do the following checks:

• the command was run in a guild
• the settings manager is not null
• the settings manager does not return null settings
• the settings returned by the manager are instances of the specified settings class

[Chew]

How does this differ from event.getClient().getSettingsFor(event.getGuild())?

[Matyrobbrt]

That method uses a generic argument which can't be inferred as it has no parameters using it. As such, it needs the type declared like .<Config>getSettingsFor(), which is annoying both to type and to look at. Plus, providing the wrong generic argument throws a class cast exception.

[Chew]

Can this be added to the Interactions class? Unless I'm missing something.