Have `npm start` comment on its own errors

[KernelDeimos]

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When running npm start, there are errors that can happen based on the environment. For example, a version of node that we don't support or packages missing because npm install wasn't run. While we should state this in the README.md file, I think it would also be very helpful if the error messages for common first-time errors that we know about are more friendly then Syntax Error: Unexpected token '?'