The source tree app crashes on a few of us at least daily.  We opened a ticket on it due to the radar in the error with Apple, but they say the error is on your end.  This is a system error saying that the system has run out of file descriptors. 

http://openradar.appspot.com/radar?id=1387401

Not sure how to upload a screen shot here with the error.
 
From our  ticket (101314148130):
I managed to get all the information out of this radar and I can confirm the following details: 
The NSPipe instances are not being deallocated immediately when you release them because they had been put into an autorelease pool (indirectly via NSTask) and won't be deallocated until the applicationDidFinishLaunching: callback is done and control returns to the runloop. If you add an autorelease pool to the interior of the loop, then the pipes and file descriptors are cleaned up before the next iteration of the loop.
 
What does this mean for you, you might ask. From Apple's point of view the behaviour is correct and this was confirmed by multiple teams and it resulted in that the radar was closed back in 2013. Since the developer simply blames it on Apple, and Apple said it that what the developer claims as the issue works as intended. 
 
So my advice would be to once again reach out to your developer and ask them to reach out to our Developer Technical Support team for proper code level support. Beyond that I don’t see any solutions for you.