admin: Catch set commands without arguments

[kwaaak]

Before:
.set
AttributeError: 'NoneType' object has no attribute 'split'

After:
.set
Owner: Usage: .set section.option value

[Exirel]

Nice catch!

I made a comment for 2 reasons:

• naming things (arg1 is not very expressive) edit: it was arg1 before, so let's keep it for now!
• readability is more important than saving one line, return should be on its own

[dgw]

@Exirel I would like to point out that arg1 was the preexisting variable name, so let's not change it in the whole command in this PR.

[Exirel]

arg1 was the preexisting variable name

Fair enough. Let's keep it that way for now then!

[kwaaak]

Philosophical question whether

return bot.say()

or

bot.say()
return

is more readable 💥

Changed it to the latter, to keep the style consistent with the rest of the file.

[Exirel]

is more readable boom

As I said on IRC, I think it's not about readability, but about intent and being explicit. My reasons is that return bot.say(...) asks these questions:

• does bot.say return something?
• does it matter?
• why a command return something, albeit being run in a separated thread?
• what's the meaning of returning something?

which is quite confusing. As pointed out by Pilate on IRC (PEP 0020):

Explicit is better than implicit

and in that regard, an empty return statement is, by convention, the explicit way to tell "stop and quit". There is extra question, no confusion possible.

That's my opinion, at least.

[dgw]

Straightforward, this is.