[sorinirimies]

Summary

Removes two unwrap()s from SpirvWatcher that could take down a long-running watch loop.

 fn watch_leaf_deps(deps)
-  for dep in deps
-    let path = dep.to_path().unwrap()     // panics on non-UTF-8 (non-Unix)
+  for path in deps.filter_map(dep_to_path) // logs + skips non-UTF-8 paths

 fn recv()
-  recv_inner(blocking).map(|r| r.unwrap())
+  loop { if let Some(r) = recv_inner(blocking)? { return Ok(r) } }

A blocking recv never reports Empty, so the loop is only reached if that invariant breaks — and waiting for the next change is the correct fallback there instead of a panic.

Evidence

New tests in watch::tests:

dep_to_path_converts_utf8_paths   ok
dep_to_path_handles_empty_path    ok
dep_to_path_non_utf8              ok   (Unix: accepted; elsewhere: None)

cargo test -p spirv-builder --features watch,clap: 7 passed. Clippy -D warnings clean. The non-Unix branch of dep_to_path_non_utf8 is exercised by Windows CI.

Merge Danger

Door: two-way

Blast Radius: small — watch feature only; behavior changes solely in the previously-panicking cases.