check err against context.Canceled error

Author: mmirolim

go/packages/packages.go

@@ -787,7 +787,7 @@ func (ld *loader) loadPackage(lpkg *loaderPackage) {
 Kind: UnknownError,
 })
 
-if ld.Context.Err() == nil {
+if err != context.Canceled {
 // If you see this error message, please file a bug.
 log.Printf("internal error: error %q (%T) without position", err, err)
 }