Keil c's switch statement causes the chip to not run normally

There is a problem

switch (opratComd)
{
    
	case COMD_Watch:
	printfStr("-------------COMD_Watch\n");
	break;

	case COMD_Open:
	printfStr("-------------COMD_Open\n");
	break;	
}

The above paragraph is missing default:break; sentence , however keil Compile without error

natural

switch (opratComd)
{
    
	case COMD_Watch:
	printfStr("-------------COMD_Watch\n");
	break;

	case COMD_Open:
	printfStr("-------------COMD_Open\n");
	break;

	default:
	return opratComd;
	break;		
}