Removes MismatchedCount argument swapping workaround

[cipharius]

It is not clear why this workaround exists here, but it seems to be outdated as of now. Instead of correcting the error message at the return site, it produces an incorrect message:

Unfortunately I could not run the test suite due to build error that I could not resolve. I will create an issue for this error.

[andyfriesen]

Well spotted!

Do you think you could toss a unit test into TypeInfer.test.cpp? It should be pretty simple to write.

Thanks!

[cipharius]

As I was trying to figure out what is expected/actual in each context, I found some other improvements to make to the MismatchedType error messages.

I will look into the CI errors, I think the MismatchedCount::Result case actually does need the swapping logic.

[cipharius]

The last error isn't related to this swapping issue anymore. It just became appearant because of the unit test improvements.

Edit:
Just realized that error originates from the newly added test case. I added it because of an error message branch in Error.cpp. Will add comment to the line in question.

[zeux]

@cipharius I believe we currently intentionally type check the program with ignored values because in some cases it's intentional, and some functions esp. in standard library may return more arguments than you realize. So this test should probably check for no errors and have a comment that it's okay to have the right hand side of the assignment to produce more values than the left hand side does.

[cipharius]

This last commit implements the suggestion made by @zeux and leaves a note on why only required values > returned values case is considered.

After the review, should I squash the commits into one, or do you prefer them to be separate?

[zeux]

There's no need to squash the commits manually - we have the repository set up so that squashes are enforced during PR merge.

[zeux]

Thanks!