Removed Errorneous Continue when Extracting Gz (#1117)

* removed errorneous continue

* found a cleaner expression to test if file exists

* add more user-friendly error

utildb/update.go

@@ -635,10 +635,8 @@ func extractTarGz(tarGzFile, outputFolder string) error {
 
 		// Make sure that output file does not overwrite existing files
 		_, err = os.Stat(targetPath)
-		if err != nil && errors.Is(err, os.ErrNotExist) { // check if not exist is clearer than check if exists
-			continue
-		} else {
-			return fmt.Errorf("Tarfile is attempting to overwrite existing file: %s", targetPath)
+		if err == nil || os.IsExist(err) {
+			return fmt.Errorf("Tarfile is attempting to overwrite existing file. This may have happened due to previous failed attempt to extract the file - consider removing the folder %s", targetPath)
 		}
 
 		// Check if it's a directory