Resolve watch situation

Author: tuguzT

crates/cargo-gpu-cache/src/build.rs

@@ -105,7 +105,7 @@ impl Build {
         self.build()
     }
 
-    /// Builds shader crate locally using [`SpirvBuilder`].
+    /// Builds shader crate using [`SpirvBuilder`].
     fn build(&self) -> anyhow::Result<()> {
         crate::user_output!(
             "Compiling shaders at {}...\n",
@@ -117,7 +117,7 @@ impl Build {
     }
 
     /// Watches shader crate for changes using [`SpirvBuilder`]
-    /// or panics depending on presence of `watch` feature.
+    /// or returns an error depending on presence of `watch` feature.
     fn watch(&self) -> anyhow::Result<()> {
         #[cfg(feature = "watch")]
         {
@@ -130,13 +130,13 @@ impl Build {
                         accept.submit(parse_result);
                     }
                 })?
-                .context("unreachable")??;
-            std::thread::park();
-            Ok(())
+                .context("should always return the first compile result")
+                .flatten()?;
+            anyhow::bail!("unexpected end of watch")
         }
 
         #[cfg(not(feature = "watch"))]
-        unreachable!("cannot watch without the `watch` feature")
+        anyhow::bail!("cannot watch for changes without the `watch` feature")
     }
 
     /// Parses compilation result from [`SpirvBuilder`] and writes it out to a file