Node.js Dock Panel object is not iterable

I’ve upgraded to @lumino/widgets 2.0.0 for my Node.js project and now my site breaks with this error:

object is not iterable
TypeError: object is not iterable
    at some (webpack-internal:///./node_modules/@lumino/widgets/node_modules/@lumino/algorithm/dist/index.es6.js:1914:25)
    at Object.postMessage (webpack-internal:///./node_modules/@lumino/widgets/node_modules/@lumino/messaging/dist/index.es6.js:222:80)
    at (webpack-internal:///./node_modules/@lumino/widgets/dist/index.es6.js:1120:68)
    at DockLayout.init (webpack-internal:///./node_modules/@lumino/widgets/dist/index.es6.js:9519:21)
    at set parent [as parent] (webpack-internal:///./node_modules/@lumino/widgets/dist/index.es6.js:1823:14)
    at set layout [as layout] (webpack-internal:///./node_modules/@lumino/widgets/dist/index.es6.js:1011:22)
    at new DockPanel (webpack-internal:///./node_modules/@lumino/widgets/dist/index.es6.js:10743:21)

The code in question causing the error is just const dock = new DockPanel(); which doesn’t seem to be wrong.

This was working just fine with version 1, and looking through the changelog and 1 => 2 upgrade guide DockPanel should still work as it did before. Has anyone run into this after upgrading? Have I stumbled onto a bug or am I just missing something glaringly obvious?

Thanks in advance!

In case someone else comes across this. Wiping out my node_modules and reinstalling dependencies finally got things working.