argparser allocator usage for the errorMessages is used inconsistently

[IntegratedQuantum]

The interface states that it should use the stackAllocator

/// `errorMessage` - out parameter used to store and return errors, if any occur. Has to be allocated with stackAllocator.

But most of the code actually uses the passed-in allocator for it which only happens to be the stack allocator (for now), and these errors are also hard to catch in a review.

I think the best solution would be to use a List instead of ListUnmanaged, so there is no chance to use the wrong allocator. The reason for using the unmanaged list is #1181.

This issue should not block the migration effort that has already started.

[Argmaster]

I just want to mention that this issue would not exist is we were to use Result struct instead of out parameter.

[IntegratedQuantum]

But Result struct would require needlessly allocating and copying the error strings around all the time right?

[Argmaster]

Would it? We could still use current approach internally, just return an Result object from the public function. I need to try to implement that to check.

[IntegratedQuantum]

What about the parse function of custom structs though?

[Argmaster]

Nothing, it gets pre-allocated list object and an appropriate allocator, so problem doesn't exist.
Problem exists only upon list creation.

[IntegratedQuantum]

I think this can wait until after #3073 and after the usages of the ArgParser helper are consilidated outside the command to reduce the number of changes needed.

[Argmaster]

A related issue: https://github.com/PixelGuys/Cubyz/pull/3112/changes#r3328982446

[IntegratedQuantum]

Yes, many of the command PRs had this problem. I decided to not worry about it in reviews to allow us to progress faster, after #3073 it should be easier to resolve all the incorrect use cases.