To know meaning of this panicString

A panic is the Unix term for an uncaught exception, sort of like a Windows Blue screen of Death. The process that caused the panic is terminated and restarted, unless it is iOS itself, in which case the phone restarts. Mere mortals like us have no way to interpret the cause of the exception without access to the iOS data dictionary. Usually even Apple developers don’t analyze the raw diagnostic file; they have AI applications that process the file and produce a human readable explanation.

It is not for you to know, the analytics are for Apple engineers and app developers.