Oops, that's a silly bug in frida-gum (sorry!), it should strip off the "L" suffix when calling toString() on a NativePointer object. As a band-aid you can either try with a 32-bit target process or locally hack it in your installed frida/core.py (just strip off the trailing "L" anywhere there's an int(a, 16) call. Expect a bugfix release tomorrow evening to fix this proper, so don't hesitate to let me know of any other issues.