op_invert breaks

[Siko91]

Hi

When I try to run a script with OP_Invert, the IDE fails.

How to reproduce: run script "f op_invert"

Output in console:

F
undefined
OP_INVERT
131
numbsys: 3

(in interpreter.js:363:8)
ReferenceError: NULL is not defined
nextStep https://siminchen.github.io/bitcoinIDE/build/script_interpreter/interpreter.js:363
nextStep https://siminchen.github.io/bitcoinIDE/build/debugger.js:115
runFromBeginning https://siminchen.github.io/bitcoinIDE/build/debugger.js:100
https://siminchen.github.io/bitcoinIDE/build/editor.js:24
jQuery 2
dispatch
handle