BrowserSync.reload causes "write after end" during gulp task - gulp

Question

I am trying to get browserSync to work with a watch task for a Polymer app. Here is my gulp file:
function source() {
return project.splitSource()
.pipe(gulpif('**/*.html', html.lint())).on('end', log('Linted HTML'))
.pipe(gulpif('**/*.html', html.minify())).on('end', log('Minified HTML'))
.pipe(gulpif('**/*.js', javascript.minify())).on('end', log('Minified Javascript'))
.pipe(gulpif('**/*.js', javascript.babelify())).on('end', log('Transpiled Javascript'))
.pipe(gulpif('**/*.{gif,jpg,svg}', images.minify())).on('end', log('Minified Images'))
.pipe(project.rejoin()); // Call rejoin when you're finished
}
function dependencies() {
return project.splitDependencies()
.pipe(project.rejoin());
}
gulp.task('default', gulp.series([
clean.build,
project.merge(source, dependencies),
project.serviceWorker
]));
gulp.task('reload', function(){
browserSync.reload();
} );
gulp.task('dev', gulp.series(
project.merge(source, dependencies)
));
gulp.task('browser-sync', function(){
return new Promise(function(resolve){
resolve( browserSync({
port: 5000,
notify: false,
logPrefix: 'PSK',
snippetOptions: {
rule: {
match: '<span id="browser-sync-binding"></span>',
fn: function(snippet) {
return snippet;
}
}
},
server: {
baseDir: ['./'],
}
})
)
});
})
gulp.task('watch', function(){
gulp.watch(['**/*.html'], gulp.series('dev','reload'));
gulp.watch(['**/*.js'], gulp.series('dev', 'reload'));
});
gulp.task('serve',
gulp.series(
'dev',
gulp.parallel('browser-sync','watch')), function(){
return gulp.src('**/*.html', {passthrough:true})
}
);
The project.splitSource is a polymer starter kit specific function that splits web components into seperate html , css, js entities so you can perform whatever tasks you need on them.
When I run 'gulp serve' , the tasks complete and my app is served.
As soon as I change the contents of a file, the watch runs the 'dev' task and attempts to run the reload task, and thats where it crashes. Here is the command line messages for this entire process :
→ gulp serve
[08:53:43] Using gulpfile ~/Documents/Projects/unicef/etools-dashboard/gulpfile.js
[08:53:43] Starting 'serve'...
[08:53:43] Starting 'dev'...
[08:53:43] Starting 'output'...
[08:55:20] Linted HTML
[08:55:20] Minified HTML
[08:55:20] Minified CSS
[08:55:20] Minified Javascript
[08:55:20] Transpiled Javascript
[08:55:20] gulp-imagemin: Minified 511 images (saved 212 kB - 3.1%)
[08:55:20] Minified Images
[08:55:29] Finished 'output' after 1.75 min
[08:55:29] Finished 'dev' after 1.75 min
[08:55:29] Starting 'browser-sync'...
[08:55:29] Starting 'watch'...
[08:55:30] Finished 'browser-sync' after 551 ms
[PSK] Access URLs:
--------------------------------------
Local: http://localhost:5000
External: http://192.168.0.102:5000
--------------------------------------
UI: http://localhost:3001
UI External: http://192.168.0.102:3001
--------------------------------------
[PSK] Serving files from: ./
[08:56:20] Starting 'dev'...
[08:56:20] Starting 'output'...
[08:56:20] Finished 'output' after 288 ms
[08:56:20] Finished 'dev' after 290 ms
[08:56:20] Starting 'reload'...
[PSK] Reloading Browsers...
Error: write after end
at writeAfterEnd (_stream_writable.js:159:12)
at StreamAnalyzer.Writable.write (_stream_writable.js:204:5)
at PassThrough.ondata (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_readable.js:546:20)
at emitOne (events.js:77:13)
at PassThrough.emit (events.js:169:7)
at readableAddChunk (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_readable.js:217:18)
at PassThrough.Readable.push (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_readable.js:176:10)
at PassThrough.Transform.push (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_transform.js:123:32)
at afterTransform (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_transform.js:79:51)
at TransformState.afterTransform (/Users/Marko1/Documents/Projects/unicef/etools-dashboard/node_modules/merge-stream/node_modules/readable-stream/lib/_stream_transform.js:58:12)
[08:56:21] The following tasks did not complete: serve, <parallel>, watch, <series>, reload
[08:56:21] Did you forget to signal async completion?
Any idea why the reload causes this to crash? I've googled this "write after end" and seems like the stream needs to be returned or async actions need an explicit done cb, but I'm not sure how to do that with gulp 4. Any advice would be of great help.