protobuf.js version: 6.3.1

In prior versions of protobufjs (4.0/5.0) this used to compile fine, and also with the google proto compiler. But when trying to generate a static module or using the json I get the following error for some fields in my .proto. All of these fields are actually nested fields like the one below:

import "net/trace/trace.proto"
package net.rpc;

message RpcDebugInfo {
  extend TraceEvent {
    optional RpcDebugInfo trace = 1008;
  }
  optional int64 size = 1;
}

This is the error:

Error: Unresolvable field type: RpcDebugInfo