TTY IO ignores most errors and busy-loops

[dcolascione]

Describe the bug
Crossterm mio backend discards all errors except would-block and interrupted, retrying immediately if anything goes wrong,.

To Reproduce
Do a TTY read in background while ignoring SIGTTIN; read gets EIO, crossterm retries constantly in a loop.

Expected behavior
A function should propagate unexpected errors to its parent.

OS
All

Terminal/Console
Codex, but should repro anywhere