Fix failing npm after git spawn change

[matijagaspar]

Fixes: #248

The issue was that:

const code = await exec(cmd, args, options)

Will throw an error if it fails to execute and the error will not contain the console output of the exec. I wrapped the bit into a try catch, so the underlying console output can be collected and put into the error message that is later handled by the outer function

[sameer-coder]

LGTM