Why am I getting so many "TypeError: vnode is null" errors?

[mitya33]

Pretty much every other error I face when building in Vue says this, and it's useless in trying to track down the problem.

I've followed the stack, but before long it just heads into lines in bundler.js i.e. Vue internals.

So how, in principle, can I figure out from such an error what's actually happening, with no meaningful feedback?
Thank you in advance.