Webpack import returns undefined, depending on the order of imports

After almost a full workday of narrowing down the issue (AKA hair-pulling), I've finally came to realize that I have a circular dependency.

Where it says // some other imports here, A imports another module C, which, in turn, imports B. A gets imported first in main.js, so B ends up being the last link in the "circle", and Webpack (or any CommonJS-like environment, for that matter, like Node) just short-circuits it by returning A's module.exports, which is still undefined. Eventually, it becomes equal to some-const, but the synchronous code in B ends up dealing with undefined instead.

Eliminating the circular dependency, by moving out the code that C depends on out of B, has resolved the issue. Wish Webpack would somehow warn me about this.

Edit: On the last note, as pointed out by @cookie, there's a plugin for circular dependency detection, if you'd like to avoid hitting this problem [again].