fix enum cast

[ureishi]

The following cast from integer 3 to TextureWrapMode will compile, but will result in an error at runtime.

code:

TextureWrapMode mode = (TextureWrapMode)3;

result:
Udon runtime exception detected!
An exception occurred during EXTERN to 'SystemObjectArray.__Get__SystemInt32__SystemObject'.
Parameter Addresses: 0x00000005, 0x00000004, 0x00000007