Add test case for checking the syntax of an empty list

[slarse]

A test just for check_syntax, which tests the corner case of an empty list (which corresponds to an empty file).

[tohanss]

One thing to do as well could be to just add an empty file to the invalid test case files

[slarse]

I think I had a reason for not doing that, but I can't recall what it was, so you could try it and see what happens.

[tohanss]

Ill keep the test, but this will not be a problem. We run the following code when sanitizing a file:

text = file_abs_path.read_text()
lines = text.split("\n")

So text becomes an empty string '' when we sanitize an empty file. Running text.split on that, however, makes lines a list containing an empty string [''] meaning lines[0] will not break if we have an empty list

[slarse]

Right, that's convenient. Might wanna put in an assert lines just to clarify that we actually expect it to be non-empty.

[slarse]

It's still a bit of an issue for check_syntax, however, as it's a public function in its module, and it will crash unexpectedly on being fed an empty list. It could potentially lead to unexpected issues down the line.