[BUG] Use EnterTransaction() before EnterLock

[Su Zoo]

Version
5.019/OS/.NET 8. (REQUIRED)

Describe the bug
When I call Upsert function in two thread, this exception might occur occasionally.

---> LiteDB.LiteException: Use EnterTransaction() before EnterLock(name)
at LiteDB.Engine.EngineState.Validate()
at LiteDB.Engine.LiteEngine.AutoTransaction[T](Func2 fn) at LiteDB.LiteCollection1.Upsert(T entity)

[Jonas Kamsker]

Could you please provide a small repro?

[Jonas Kamsker]

The bug should have been resolved in v5.0.20