This does two big things:
- We add custom error messages and conversions from other error types
into our own error type. This means we can create or modify more
fine grained errors rather than using whatever `failure::Error` gives
us. The first one we have is a `Cli` error, whereby calls to things
like wasm-bindgen or npm failed.
- We also make it so that `PBAR.error()` is called only on exit. We grab
a reference to whatever error gets passed up the chain, have it
generate a message to be printed as an error to PBAR, close up PBAR
like normal, and then print our actual error message to stderr!
The main benefits of this is that as long as we return an error, PBAR
will print and close itself up and we don't need to call it every time
or forget that we would need to call it, and we put error details
specifically into our error!
Closes#12
Michael Gattozzi