internal/exportdata: add missing return

Change-Id: I9703c6a4a2ae4a608d33cf706106c92e9bd2aef7
GitHub-Last-Rev: 3eee41957d8a2d9908519c798f30d5ccc90c53fb
GitHub-Pull-Request: golang/go#71096
Reviewed-on: https://go-review.googlesource.com/c/go/+/637962
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

src/internal/exportdata/exportdata.go

@@ -85,6 +85,7 @@ func ReadUnified(r *bufio.Reader) (data []byte, err error) {
 
 	if n < 0 {
 		err = fmt.Errorf("invalid size (%d) in the archive file: %d bytes remain without section headers (recompile package)", size, n)
+		return
 	}
 
 	// Read n bytes from buf.