Incorrect typing of Struct.toJson() about protobuf-es

[timostamm]

Also see: #508

[CharlieMartell]

Well this isn't about a better typing to the JSON its just that the return value of this fn is just wrong. It only ever returns a JsonObject type

[timostamm]

It is not wrong because a JsonObject is a JsonValue. Here's the definition:

export type JsonValue =
  | number
  | string
  | boolean
  | null
  | JsonObject
  | JsonValue[];

export type JsonObject = { [k: string]: JsonValue };

All messages actually return a JsonObject, the only exception are a handful of well-known types. We use JsonValue for both sides for symmetry, it was never intended to provide message-specific type information.