2.9.2 not working with 'exactOptionalPropertyTypes: true'

[steida]

"Type 'EncryptedMessage$Type' is not assignable to type 'IMessageType' with 'exactOptionalPropertyTypes: true'. Consider adding 'undefined' to the types of the target's properties.\n Types of property 'messagePrototype' are incompatible.\n Type 'Readonly<{}> | undefined' is not assignable to type 'Readonly<{}>'.\n Type 'undefined' is not assignable to type 'Readonly<{}>'.",

2.9.1 is OK

[jcready]

This was my fault as there was a different property type definition between the IMessageType interface and the MessageType class which implements it for the newly added messagePrototype field. I apologize for the breakage and I've opened a PR which should fix the issue.