Folding exponent can make the compiler crash

[trocher]

Version Information

• vyper Version (output of vyper --version OR linkable commit hash vyperlang/vyper@commitish): 0.4.0rc3+commit.6d4c09cd

Issue description

When having x ** y folded, if x == 0 or x == 1, the compiler will crash.

See:

https://github.com/vyperlang/vyper/blob/6d4c09cda518ffce81a9a76f822059fdce16cdfb/vyper/ast/nodes.py#L1105-L1106

POC

@external
def foo()->uint256:
   return 1**2

ZeroDivisionError: float division by zero

@external
def foo()->uint256:
   return 0**2

ValueError: math domain error