Zig: zeroes(@OpaqueType()) triggers assertion in compiler.

[JesseRMeyer]

var widely_regarded_as_a_bad_move = zeroes(@OpaqueType());

Assertion failed at D:\a\1\s\src\analyze.cpp:1003 in get_fn_type. This is a bug in the Zig compiler.
Unable to dump stack trace: debug info stripped

While that code is total nonsense, it shouldn't crash the compiler. 0.5.0+68dbba212

[xackus]

I'd like to tackle this as my first stage1 issue.