fix: command line bugs when run pxt init

[TbhT]

when i test pxt init in the doc of the website https://makecode.com/cli，it happens as bellow:

➜  pxt init
Using target microbit with build engine yotta
  target: v4.0.12 ****/pxt-t1/node_modules/pxt-microbit
  pxt-core: v7.0.8 *****/pxt-t1/node_modules/pxt-core
name [blink]: 
description []: hello
license [undefined]: MIT
installing dependencies...
INTERNAL ERROR: TypeError: Cannot read property 'flags' of undefined
    at installAsync (****/pxt-t1/node_modules/pxt-core/built/pxt.js:156876:24)
    at *****/pxt-t1/node_modules/pxt-core/built/pxt.js:157023:21
    at processTicksAndRejections (internal/process/task_queues.js:95:5)

and it seems like a pxt-cli bugs in pxt repo that the parsed variable can not be found , when installAsync() called without any params.