Missing script "working-json.js" from ace is causing error

[bjost2s]

When loading the Open Roberta Lab you will find the following error message in the console:

It tries to load the script from ace but we do not have it in the static resources. It only happens when selecting a robot which has JSON as source code format, e.g. WeDo

[NiHoffmann]

Issue fix on branch:
feature/Issue1689