CodegenPanic for slice on empty(Bytes)

[cyberthirst]

Version Information

• vyper Version (output of vyper --version OR linkable commit hash vyperlang/vyper@commitish): 0.4.0rc3+commit.80708e6d

Issue description

Certain contracts which contain empty and slice fail to compile.

POC

This contract

#@version 0.4.0.rc3

@external
def foo():
    s: Bytes[2] = slice(empty(Bytes[4]), 0, 2)

fails to compile with:

vyper.exceptions.CodegenPanic: unhandled exception ~empty <empty(Bytes[4])>, parse_Call

credits: @trocher