Ensure thrown errors always bubble to the extension appropriately

[darkwing]

I haven't been able to determine if this problem is on the extension or keyring side, but it seems as though every error that occurs with Ledger integration makes its way to the extension UI as Internal JSON-RPC error., which is incredibly unhelpful for the dev teams and users being able to report issues.

This should be a top priority moving forward with Ledger work.