Delegate valid checking to the compiler

[Denneisk]

1. Deduplicates a lot of code
2. Can optimize by caching (most likely per block, and would need destructive functions to invalidate the cache somehow (attribute? context method?))

[Vurv78]

Need more detail on what you mean here

[Denneisk]

https://github.com/wiremod/wire/blob/master/lua/entities/gmod_wire_expression2/core/entity.lua#L105

if not IsValid(this) then return self:throw("Invalid entity!", "") end

These sorts of checks (similar can be found in EGP extensions, wirelink, etc.).

[thegrb93]

As long as there's a way to disable the check for cases where an invalid entity is allowable.