Incorrect typing of Struct.toJson()

[CharlieMartell]

Describe the bug

Here: https://github.com/bufbuild/protobuf-es/blob/main/packages/protobuf/src/google/protobuf/struct_pb.ts#L72 we see that this function returns a JsonValue type but in the implementation it should return a JsonObject type. This means consuming applications need get type errors when doing anything like Object.entries(struct.toJson())

Environment (please complete the following information):

• @connectrpc/connect-web version: 1.8.0
• Frontend framework and version: react@18
• Node.js version: node@20
• Browser and version: Chrome

[srikrsna-buf]

Hey! Can you open the issue in https://github.com/bufbuild/protobuf-es? But the tl;dr answer is it is done for symmetry and will likely be solved alongside bufbuild/protobuf-es#508