added null checking to loadingContainerState in dismiss method to prevent loading not getting remove

[sckoh]

if the below code is called consecutively, the loading container will not be removed due to loadingContainerState is null and the completer future will not be completed.

EasyLoading.show();
EasyLoading.dismiss();

null checking is added to loadingContainerState in dismiss method to prevent loading not getting remove

[nslogx]

thanks

[bhargavsejpalindianic]

any chance to prevent from remove on click of hardware back button