Hi,
We understand that you are not using any NXP RTD packages, is this correct? Are you using any NXP development board? Or is this a custom board?
For what we can provide, reaching an undefined_handler scenario can range from the IRQ handler not being defined correctly (or not defined at all) to the IRQ not being installed correctly or in the correct order. Following the example available under the RTD, the following sequence is followed:

Given that, if true, you are not using any NXP packages, we cannot confirm if these are the possible problems that you have. We do apologize.
We can also recommend contacting your local NXP FAE/DFAE, they could possibly provide more insight on your current situation.
Please, let us know.