fix: improve error handling/reporting and prevent premature exit in dev mode

[chrispcampbell]

Fixes #260

@ToddFincannonEI: The gory details are in the issue, but TL;DR this improves error handling in a number of areas to:

1. add error handling in places where we didn't have it quite right (like in readDat) and
2. avoid process.exit and instead allow errors to bubble up and get reported in a standard way

[ToddFincannonEI]

Improved error handling is long overdue. I like what you've done here. I reviewed the changes in the compile package, since I am not that familiar with the new packages. Letting exceptions bubble up instead of calling process.exit() seems obvious in retrospect!