FWIW, this is not a "thread error". The error message is just telling which thread happened to be running when the error occurred.
What terminated your app is a SIGABRT, which indicates almost certainly that your app invoked the "abort()" function to kill itself after encountering a condition it couldn't recover from.
You should look in the debugger for the backtrace of that thread (or look in the crash log, if you weren't running via Xcode at the time of the crash), and work your way up to find the line of your source code where the error is detected. This might be a call to "precondition", or it may be something in generated code, but whatever crashes will typically "print" an error message to the console log. The combination of error message and location within your source code should help you figure out exactly what went wrong.
My guess, in this case, is that UITableView threw an Objective-C NSException, because there's something wrong with the way your table view is set up. The default handling of a NSException is to crash your app.