Type guard function to determine if an OutPayload is a message-based payload.
Checks whether the payload uses the newer msg field format for message type identification. This is used to
differentiate between different payload structures and ensure proper type narrowing in TypeScript.
Type guard function to determine if an OutPayload is a message-based payload.
Checks whether the payload uses the newer msg field format for message type identification. This is used to differentiate between different payload structures and ensure proper type narrowing in TypeScript.