figured out the problem so i'll post here for others. the app puts up two different 'completion' dialog boxes. the first one say "done." and give you completion time, a few moments later it changes to another one that says "successful". If you click Close on the first one, the app will error out when it tries to run the code for the second one. If you always wait on the 2nd dialog, it will not crash, if you click close on the first one, it will always crash a moment later.
Starting today, the joiner app suddenly exits after it finishes the joining process. The files process fine but the app just closes and I have to launch again. Yesterday, and prior days, it did not do this. Not sure if there is a log file somewhere that will indicate the issue but curious if others have seen this situation? Thanks in advance for any time or help.