If an empty EventContainer is included into another, do nothing instead of raising an error
If an empty EventContainer is included into another, do nothing instead of raising an error

Roughsketch/discordrb,megumisonoda/discordrb,Roughsketch/discordrb,megumisonoda/discordrb,VxJasonxV/discordrb,VxJasonxV/discordrb,meew0/discordrb,meew0/discordrb