Flutter在使用GlobalKey().currentState.showBottomSheet实现BottomSheet:底部滑动窗口 出现如下报错
The method 'showBottomSheet' can't be unconditionally invoked because the receiver can be 'null'.\
Try making the call conditional (using '?.') or adding a null check to the target ('!').
解决办法：向目标中添加一个空检查('!')
.currentState.showBottomSheet
