Avoid panicking when the resolver thread encounters a closed channel

crates/uv-resolver/src/resolver/mod.rs

@@ -267,18 +267,25 @@ impl<Provider: ResolverProvider, InstalledPackages: InstalledPackagesProvider>
         let solver = state.clone();
         let index_locations = provider.index_locations().clone();
         let (tx, rx) = oneshot::channel();
-        thread::Builder::new()
+        let handle = thread::Builder::new()
             .name("uv-resolver".into())
             .spawn(move || {
                 let result = solver.solve(index_locations, request_sink);
-                tx.send(result).unwrap();
+                tx.send(result)
             })
             .unwrap();
 
         let resolve_fut = async move { rx.await.map_err(|_| ResolveError::ChannelClosed) };
 
         // Wait for both to complete.
         let ((), resolution) = tokio::try_join!(requests_fut, resolve_fut)?;
+
+        // Retrieve a possible send error from the solver thread
+        handle
+            .join()
+            .unwrap()
+            .map_err(|_| ResolveError::ChannelClosed)?;
+
         state.on_complete();
         resolution
     }