http://hastebin.com/iviloduseg.vhdl
how do i fix that im not too sure why that happening

Looks like the block skins in your world somehow became corrupt. I will add a check for this in the next update so it does not crash.

Do you know how the blocks became corrupted? Would help to know.

sadly I don't know

i found it here a screenshot i made its invisible block http://puu.sh/kP2bn/8880ce9de5.png when i pick it up it look like this http://puu.sh/kP2fa/6ec1113156.png