Throw explained lambda error (#3130 #3308)

[Zvbhrf]

Fixes #3130 and #3308

(Sorry, I messed commit history a bit :P)

[Denneisk]

I'm still a supporter for the previous compiler writer's reason for not including this check, but I won't be too resistant if people still want it.

[Zvbhrf]

I'm still a supporter for the previous compiler writer's reason for not including this check, but I won't be too resistant if people still want it.

I've already been confused a few times (I thought I found a bug) until I opened the compiler.lua file and Wiremods issues.
I decided to add an error which say for sure: something is wrong in your lambda, not in the compiler itself.
We must remember that there are many of players who don't know Lua and that GitHub exists. They will probably be more confused than I am when getting Lua errors during compilation.