pbjs: generate json-module target

[halex2005]

protobuf.js version: v6.4.1

I use

node_modules/protobufjs/bin/pbjs -p ./proto -o protoclasses-module.js -t json-module --no-delimited ./proto/**/*.proto

to generate javascript module.
Generated code has bootstrapper:

module.exports = factory(require("protobufjs/runtime"));

where the factory is

function($protobuf) {
    "use strict";
    var $root = protobuf.Root.fromJSON({

but protobufjs/runtime has no Root property exported and I get runtime error

/home/hal/git/diadocsdk-proto/protoclasses-module.js:8
        module.exports = factory(require("protobufjs/runtime"));
                         ^
TypeError: Cannot read property 'fromJSON' of undefined
    at /home/hal/git/diadocsdk-proto/protoclasses-module.js:13:30

So, I can fix this by require('protobufjs'), not require('protobufjs/runtime').
Or I can make PR with Root exported from runtime.
Which is correct usage scenario for protobuf/runtime here?