[BUG] DivExpression problem on division by 0

[britzl]

Describe the bug
The DivExpression in ast.lua has a simplify argument which will perform the division and store the result if both left and right-hand side of the expression is a constant. This works great in all cases except when dividing by 0.

print(1/0) -- inf
print(-1/0) -- -inf
print(0/0) -- nan

The above three expressions return constants inf and nan of type number. The problem when simplifying this is that the resulting string will become:

print(inf) -- nil
print(-inf) -- attempt to perform arithmetic on global 'inf' (a nil value)
print(nan) -- nil

Expected behavior
The DivExpression should not simplify the expression when the right hand side is 0.

To Reproduce
Steps to reproduce the behavior:

• Create a file divexpression.lua containing print(-1/0)
• Run lua cli.lua --preset Weak divexpression.lua

Observe divexpression.obfuscated.lua