Module diag 

Diagnostic output that cannot take the application down with it.

eprintln! ends in the standard library’s print_to, whose last act is panic!("failed printing to {label}: {e}"). A Tilo application is launched with its stderr on a pipe the compositor reads, so when that reading end goes away the next write returns EPIPE and that panic fires — under the release profile’s panic = "abort", instantly and without unwinding. A diagnostic line then kills the program it was describing, and its window is left on screen with no process behind it.

diag! is eprintln! with the write error dropped. Use it wherever an app or the toolkit would reach for eprintln!; tracing needs no such treatment, its writers already discard I/O errors.

Functions

write_line

Write one diagnostic line to stderr, discarding any write error.