AssertionError: Assertion failed when deserializing message from python in js

Beginne mit dem verknüpften Beispiel-Repository und führe nach der Installation seiner Anforderungen node test.js und python3 test.py aus. Vergleiche den Deserialisierungspfad in demo_pb.js mit dem Python-Ergebnis und verwende dabei die gemeldete Bytefolge und den Stacktrace als Reproduktion. Als abgeschlossen gilt die Aufgabe, wenn die Nachricht sowohl in JavaScript als auch in Python erfolgreich deserialisiert wird, ohne dass der AssertionError auftritt.

What version of protobuf and what language are you using?
Version: v.3.11.2
Language: Python, Javascript

What operating system (Linux, Windows, ...) and version?
MacOS High Sierra Version 10.13.6

What runtime / compiler are you using (e.g., python version or gcc version)
Python 3.7.3, NodeJS v13.3.0

What did you do?
Steps to reproduce the behavior:

1. Defined these protos:

syntax = "proto2";

message B {
  optional string b2 = 2;
}

message A {
  optional B b = 1;
  optional string id = 2;
}

2. Attempted to deserialize this message in both js and python: 0a060a0131120131181e10a3c6ad8dcdeed0a274

Here's a sample repo to reproduce: https://github.com/bhainesva/protobuf-py-vs-js-demo (run node test.js / python3 test.py after installing requirements).

What did you expect to see
I expected the deserialization to succeed in both python and js.

What did you see instead?
Python deserialization succeeds but js deserialization produces this error:

/Users/bhaines/repo/proto-demo/node_modules/google-protobuf/google-protobuf.js:81
jspb.BinaryConstants.TWO_TO_32=4294967296;jspb.BinaryConstants.TWO_TO_52=4503599627370496;jspb.BinaryConstants.TWO_TO_63=0x7fffffffffffffff;jspb.BinaryConstants.TWO_TO_64=1.8446744073709552E19;jspb.BinaryConstants.ZERO_HASH="\x00\x00\x00\x00\x00\x00\x00\x00";goog.dom={};goog.dom.NodeType={ELEMENT:1,ATTRIBUTE:2,TEXT:3,CDATA_SECTION:4,ENTITY_REFERENCE:5,ENTITY:6,PROCESSING_INSTRUCTION:7,COMMENT:8,DOCUMENT:9,DOCUMENT_TYPE:10,DOCUMENT_FRAGMENT:11,NOTATION:12};goog.debug={};goog.debug.Error=function(a){if(Error.captureStackTrace)Error.captureStackTrace(this,goog.debug.Error);else{var b=Error().stack;b&&(this.stack=b)}a&&(this.message=String(a));this.reportErrorToServer=!0};goog.inherits(goog.debug.Error,Error);goog.debug.Error.prototype.name="CustomError";goog.asserts={};goog.asserts.ENABLE_ASSERTS=goog.DEBUG;goog.asserts.AssertionError=function(a,b){goog.debug.Error.call(this,goog.asserts.subs_(a,b));this.messagePattern=a};goog.in
Error [AssertionError]: Assertion failed
    at new goog.asserts.AssertionError (/Users/bhaines/repo/proto-demo/node_modules/google-protobuf/google-protobuf.js:81:876)
    at Object.goog.asserts.doAssertFailure_ (/Users/bhaines/repo/proto-demo/node_modules/google-protobuf/google-protobuf.js:82:257)
    at Object.goog.asserts.assert (/Users/bhaines/repo/proto-demo/node_modules/google-protobuf/google-protobuf.js:83:83)
    at jspb.BinaryReader.readString (/Users/bhaines/repo/proto-demo/node_modules/google-protobuf/google-protobuf.js:394:64)
    at Function.proto.A.deserializeBinaryFromReader (/Users/bhaines/repo/proto-demo/demo_pb.js:263:49)
    at Function.proto.A.deserializeBinary (/Users/bhaines/repo/proto-demo/demo_pb.js:239:18)
    at Object.<anonymous> (/Users/bhaines/repo/proto-demo/test.js:13:20)
    at Module._compile (internal/modules/cjs/loader.js:1128:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1167:10)
    at Module.load (internal/modules/cjs/loader.js:983:32) {
  message: 'Assertion failed',
  reportErrorToServer: true,
  messagePattern: 'Assertion failed'
}

Seems related to including unknown fields in messages but I'm not very familiar with protobuf, my understanding is that that's supported.

Potentially related to this issue? protocolbuffers/protobuf#4688.