You are calling an instance that is not yet ready.
The issue is this instance
/// Intial Clean for SDK
static _intialCleanUp() {
// Remove all the Syncing State Message (Unsend messages)
serviceLocator()
.getUnsendMessages()
.forEach((element) => element.delete());
}
Please can you correct this and upload a new version to pub.dev
I can bypass this slightly for now but it needs to be adressed.
Also, create a category for Flutter in this forum…