From Xojo Documentation
| This item was deprecated in version 2019r2.
Please use Exception Handling as a replacement.
Reports the last file I/O error. Error numbers are given as original file system error codes.
For BinaryStream objects created with a String, all errors return 100. This happens if you try to write to or set the length of the BinaryStream.
This code gets the last error code. If there is no error code, LastErrorCode returns 0.