Interrupt vector address in Program Counter?
The PC is never loaded with the value 0x00000048. The second image shows

PC = {0x00000048}


which is their way of saying (using the { and } characters) that the PC is loaded with the contents of memory location 0x00000048. The result is that the processor jumps straight to the start of your service routine.

That's also why the first image shows "Vector location" at the top of the column rather than "Handler address" or something similar.

By the way, the full correct part number for your device is TM4C123GH6PM.

You can find the manufacturers data sheet here.