Improvement: Show original source file and line number on errors

[jvolker]

Follow up from #56. Sometimes during development you get errors like the following:

(node:6870) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 2): undefined
(node:7167) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): SyntaxError: Unexpected token var

It's hard to understand where they come from as they don't mention the original source file and line number. Is there any way to display the original source file and line number?

Thanks.

[aubergene]

I followed the install instructions and got a similar error

setterm: terminal xterm-256color does not support --blank
setterm: cannot (un)set powersave mode: Inappropriate ioctl for device
pi@raspberrypi:~ $ openframe


(node:4517) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): TypeError: Cannot read property 'download' of undefined