Useless encoded data

[osechet]

protobuf.js version: 6.3.1

Using the following message,

message Response {
    fixed32 id = 1;
    bytes data = 2;
    string error = 3;
}

when calling Response.encode(Response.create({error: 'error'})).finish(), I get: [18, 0, 26, 5, 101, 114, 114, 111, 114].

The 2 first bytes are useless.

If I call Response.encode({error: 'error'}).finish(), I get [26, 5, 101, 114, 114, 111, 114] which is fine.