An error occurred because the file you are currently running calls to core_cm3.h, and core_cm3.h file contains the type name has IRQn_Type, but this type of name is defined in the "stm32f10x.h" in, so you need to include in the current file # include "core_cm3.h" before the first contains #include "stm32f10x.h"
Remember, two header files will be given if the wrong order
#include "stm32f10x.h" #include "core_cm3.h"