show monaco toolbox for "main.ts" only + some defensive checks (#4647)
show monaco toolbox for "main.ts" only + some defensive checks (#4647)


playi/pxt,Microsoft/pxt,switch-education/pxt,switch-education/pxt,switchinnovations/pxt,Microsoft/pxt,playi/pxt,Microsoft/pxt,switchinnovations/pxt,switch-education/pxt,playi/pxt,switchinnovations/pxt,playi/pxt,switchinnovations/pxt,switch-education/pxt,Microsoft/pxt,switch-education/pxt,Microsoft/pxt