go/runtime/bundle: Fix comments and errors

go/runtime/bundle/discovery.go

@@ -449,7 +449,7 @@ func (d *Discovery) copyBundle(src string) error {
 			"src", src,
 			"dst", dst,
 		)
-		return fmt.Errorf("failed to open bundle: %w", err)
+		return fmt.Errorf("failed to copy bundle: %w", err)
 	}
 
 	d.logger.Info("bundle copied",

go/runtime/bundle/registry.go

@@ -106,7 +106,8 @@ func (r *registry) AddBundle(path string, manifestHash hash.Hash) error {
 	}
 	defer bnd.Close()
 
-	// Verify manifest hash.
+	// Verify that the manifest hash belongs to the bundle before checking
+	// if the bundle is already in the registry.
 	if !bnd.manifestHash.Equal(&manifestHash) {
 		return fmt.Errorf("invalid manifest hash (got: '%s', expected: '%s')",
 			bnd.manifestHash.Hex(),
@@ -119,7 +120,8 @@ func (r *registry) AddBundle(path string, manifestHash hash.Hash) error {
 		return nil
 	}
 
-	// Verify that components are unique.
+	// Ensure the manifest doesn't include a component version already
+	// in the registry.
 	components := bnd.Manifest.GetAvailableComponents()
 
 	for compID, comp := range components {