StaffTestComplete shows the command that posted error message to the test execution log.
I can recommend you to temporarily remove/comment try-catch statement, then run your test and if the error will occur again then TestComplete will show you the run-time error message and the corresponding script line.
With the error row selected in your log file, go to the Call Stack tab at the bottom. It'll give you the sequence of methods called prior to the error. This is helpful when the error occurs in a generic function. The top row will be the same location you get when you double click the error row in the log, the next row in the Call Stack will be the method that called the method that errored, and so on.
