message: Fix Strictmode erro
  types(src): remove "?" from the new "Ref" type
diff: @@ -278,7 +278,7 @@ export type RefSchemaType = typeof mongoose.Schema.Types.Number |
  * @public
  */
  // export type Ref<R, T extends RefType = mongoose.Types.ObjectId> = R | T; // old type, kept for easy revert
  -export type Ref<R, T extends RefType = R extends { _id?: RefType; } ? R['_id'] : mongoose.Types.ObjectId> = R | T;
  +export type Ref<R, T extends RefType = R extends { _id: RefType; } ? R['_id'] : mongoose.Types.ObjectId> = R | T;
  /**
  * An Function type for a function that dosnt have any arguments and dosnt return anything
  