Improve copy function error checking + delete make fuzz because of golang/go#52569

Author: ddworken

Makefile

@@ -5,9 +5,6 @@ forcetest:
 test:
 	HISHTORY_TEST=1 go test -p 1 ./...
 
-fuzz:
-	HISHTORY_TEST=1 go test -p 1 -fuzz=FuzzTestMultipleUsers -run FuzzTestMultipleUsers client/client_test.go
-
 acttest:
 	act push -j test -e .github/push_event.json --reuse --container-architecture linux/amd64
 

client/lib/lib.go

@@ -634,9 +634,13 @@ func copyFile(src, dst string) error {
 	if err != nil {
 		return err
 	}
-	defer destination.Close()
+
 	_, err = io.Copy(destination, source)
-	return err
+	if err != nil {
+		return err
+	}
+
+	return destination.Close()
 }
 
 func GetDownloadData() (shared.UpdateInfo, error) {