Deno node-minecraft-protocol bug report (Adapted from https://github.com/PrismarineJS/node-minecraft-protocol/blob/master/examples/server_world/mc.js)

deno.js

import mc from "npm:minecraft-protocol";
import PrismarineChunk from "npm:prismarine-chunk";
import Vec3 from "npm:vec3";
import MCData from "npm:minecraft-data";

const mcData = MCData('1.16.5')
const Chunk = PrismarineChunk('1.16.5')
const server = mc.createServer({
  'online-mode': true,
  encryption: true,
  host: '0.0.0.0',
  port: 25565,
  version: '1.16.5'
})
const loginPacket = mcData.loginPacket
const chunk = new Chunk()

for (let x = 0; x < 16; x++) {
  for (let z = 0; z < 16; z++) {
    chunk.setBlockType(new Vec3(x, 100, z), mcData.blocksByName.grass_block.id)
    chunk.setBlockData(new Vec3(x, 100, z), 1)
    for (let y = 0; y < 256; y++) {
      chunk.setSkyLight(new Vec3(x, y, z), 15)
    }
  }
}

server.on('playerJoin', function (client) {
  client.write('login', {
    ...loginPacket,
    entityId: client.id,
    isHardcore: false,
    gameMode: 0,
    previousGameMode: 1,
    worldName: 'minecraft:overworld',
    hashedSeed: [0, 0],
    maxPlayers: server.maxPlayers,
    viewDistance: 10,
    reducedDebugInfo: false,
    enableRespawnScreen: true,
    isDebug: false,
    isFlat: false
  })
  client.write('map_chunk', {
    x: 0,
    z: 0,
    groundUp: true,
    biomes: chunk.dumpBiomes !== undefined ? chunk.dumpBiomes() : undefined,
    heightmaps: {
      type: 'compound',
      name: '',
      value: {} // Client will accept fake heightmap
    },
    bitMap: chunk.getMask(),
    chunkData: chunk.dump(),
    blockEntities: []
  })
  client.write('position', {
    x: 15,
    y: 101,
    z: 15,
    yaw: 137,
    pitch: 0,
    flags: 0x00
  })
})

node.js

const mc = require("minecraft-protocol");
const PrismarineChunk = require("prismarine-chunk");
const Vec3 = require("vec3");
const MCData = require("minecraft-data");

const mcData = MCData("1.16.5");
const Chunk = PrismarineChunk("1.16.5");
const server = mc.createServer({
	"online-mode": true,
	encryption: true,
	host: "0.0.0.0",
	port: 25565,
	version: "1.16.5",
});
const loginPacket = mcData.loginPacket;
const chunk = new Chunk();

for (let x = 0; x < 16; x++) {
	for (let z = 0; z < 16; z++) {
		chunk.setBlockType(new Vec3(x, 100, z), mcData.blocksByName.grass_block.id);
		chunk.setBlockData(new Vec3(x, 100, z), 1);
		for (let y = 0; y < 256; y++) {
			chunk.setSkyLight(new Vec3(x, y, z), 15);
		}
	}
}

server.on("playerJoin", function (client) {
	client.write("login", {
		...loginPacket,
		entityId: client.id,
		isHardcore: false,
		gameMode: 0,
		previousGameMode: 1,
		worldName: "minecraft:overworld",
		hashedSeed: [0, 0],
		maxPlayers: server.maxPlayers,
		viewDistance: 10,
		reducedDebugInfo: false,
		enableRespawnScreen: true,
		isDebug: false,
		isFlat: false,
	});
	client.write("map_chunk", {
		x: 0,
		z: 0,
		groundUp: true,
		biomes: chunk.dumpBiomes !== undefined ? chunk.dumpBiomes() : undefined,
		heightmaps: {
			type: "compound",
			name: "",
			value: {}, // Client will accept fake heightmap
		},
		bitMap: chunk.getMask(),
		chunkData: chunk.dump(),
		blockEntities: [],
	});
	client.write("position", {
		x: 15,
		y: 101,
		z: 15,
		yaw: 137,
		pitch: 0,
		flags: 0x00,
	});
});