第二次复制文件时，Swfit FileManager与EXC_BAD_ACCESS崩溃

I'm writing a MacOS application with a process that creates a temp folder in the Application Support directory, generates a few new files in that folder and then also copies some user-specified files into it, and then finally copies the full contents of my temp folder into a user-specified final location. Everything works perfectly the first time you run this export process after launching the app, but crashes with an EXC_BAD_ACCESS error if it gets run more than once. The application-generated files are always created and written fine, but the crash always occurs when the FileManager attempts to copy one of the existing user-selected files, even though it passes my guard statements checking that the existing file is readable and the destination path is writable. If you re-launch the app, it will again run the first time no problem, but crashes the second.I'm writing a MacOS application with a process