encoding/gob: properly ignore errors

Change-Id: I8827cef0f57459384329c50c51795350da0ede4b
GitHub-Last-Rev: c9ad9e12b5a0fff47c21a8c299b762b64b8c9c7c
GitHub-Pull-Request: golang/go#30010
Reviewed-on: https://go-review.googlesource.com/c/go/+/160434
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>

src/encoding/gob/decgen.go

@@ -185,10 +185,12 @@ func main() {
 		log.Fatal("source format error:", err)
 	}
 	fd, err := os.Create(*output)
-	_, err = fd.Write(source)
 	if err != nil {
 		log.Fatal(err)
 	}
+	if _, err := fd.Write(source); err != nil {
+		log.Fatal(err)
+	}
 }
 
 func printMaps(b *bytes.Buffer, upperClass string) {

src/encoding/gob/encgen.go

@@ -164,10 +164,12 @@ func main() {
 		log.Fatal("source format error:", err)
 	}
 	fd, err := os.Create(*output)
-	_, err = fd.Write(source)
 	if err != nil {
 		log.Fatal(err)
 	}
+	if _, err := fd.Write(source); err != nil {
+		log.Fatal(err)
+	}
 }
 
 func printMaps(b *bytes.Buffer, upperClass string) {