fix(bundle): properly display error on invalid config in watch mode (#30621)

Fixes https://github.com/denoland/deno/issues/30617

cli/tools/bundle/mod.rs

@@ -184,6 +184,16 @@ pub async fn bundle(
   let duration = end.duration_since(start);
 
   if bundle_flags.watch {
+    if !response.errors.is_empty() || !response.warnings.is_empty() {
+      handle_esbuild_errors_and_warnings(
+        &response,
+        &init_cwd,
+        &bundler.plugin_handler.take_deferred_resolve_errors(),
+      );
+      if !response.errors.is_empty() {
+        deno_core::anyhow::bail!("bundling failed");
+      }
+    }
     return bundle_watch(
       flags,
       bundler,
@@ -400,7 +410,8 @@ impl EsbuildBundler {
       .client
       .send_build_request(self.make_build_request())
       .await
-      .unwrap();
+      .unwrap()
+      .map_err(|e| message_to_error(&e, &self.cwd))?;
 
     Ok(response)
   }
@@ -411,7 +422,13 @@ impl EsbuildBundler {
         panic!("rebuild not supported for one-shot mode")
       }
       BundlingMode::Watch => {
-        let _response = self.client.send_rebuild_request(0).await.unwrap();
+        log::trace!("sending rebuild request");
+        let _response = self
+          .client
+          .send_rebuild_request(0)
+          .await
+          .unwrap()
+          .map_err(|e| message_to_error(&e, &self.cwd))?;
         let response = self.on_end_rx.recv().await.unwrap();
         Ok(response.into())
       }
@@ -419,6 +436,13 @@ impl EsbuildBundler {
   }
 }
 
+fn message_to_error(
+  message: &esbuild_client::protocol::Message,
+  current_dir: &Path,
+) -> AnyError {
+  deno_core::anyhow::anyhow!("{}", format_message(message, current_dir))
+}
+
 // TODO(nathanwhit): MASSIVE HACK
 // See tests::specs::bundle::requires_node_builtin for why this is needed.
 // Without this hack, that test would fail with "Dynamic require of "util" is not supported"