debugAssertDoesMeetConstraints method Null safety
override
Verify that the object's constraints are being met. Override this function in a subclass to verify that your state matches the constraints object. This function is only called in checked mode and only when needsLayout is false. If the constraints are not met, it should assert or throw an exception.
Implementation
@override
void debugAssertDoesMeetConstraints() { assert(false); }