hi,when i config lpuart2
```
LPUART_Type *base = g_lpuartBase[INST_LPUART2];
LPUART_DRV_Init(INST_LPUART2, &lpuart2_State, &lpuart2_InitConfig0);
INT_SYS_InstallHandler(g_lpuartRxTxIrqId[INST_LPUART2], DEBUG_DRV_IRQHandler, (isr_t *) 0);
INT_SYS_SetPriority(LPUART2_RxTx_IRQn, 2);
/* Enable the receive data overrun interrupt */
LPUART_SetIntMode(base, LPUART_INT_RX_OVERRUN, true);
/* Enable the receive data overrun interrupt */
LPUART_SetIntMode(base, LPUART_INT_FRAME_ERR_FLAG, false);
/* Enable receive data full interrupt */
LPUART_SetIntMode(base, LPUART_INT_RX_DATA_REG_FULL, true);
```
in this code
```
LPUART_SetIntMode(base, LPUART_INT_RX_DATA_REG_FULL, true);
```
it willl go to this breakpoint,frame error, why ,and use api get receive byte is zero, why ?
```
uint8_t rb;
LPUART_Getchar(base, &rb)
```
rb result is zero
