Error boundaries and instrumentation

Failing in one place instead of everywhere

An error file wraps its segment in a boundary, so a crash in one panel leaves the rest of the page usable and offers a retry. Without it, a single thrown error replaces the whole application with a blank screen.

Boundaries are per segment, which means placement is a design decision. A boundary at the root is a safety net; a boundary around each widget is a resilient dashboard.

Expected failures are not errors. A record that does not exist should call notFound(), not throw — mixing the two floods your error reporting with 404s and buries the real bugs.