Make sure findOne throws if no elements are found

[twokul]

If you have the following code:

// in this case, `findOne` couldn't find any elements with `displayName: 'some name'`
PAGE.elements.findOne({ displayName: 'some name' }).anotherElement.click()

it throws with not very helpful message: Cannot read property 'anotherElement' of undefined.

This change adds a more helpful error: Expected at most one result from 'findOne' query in 'elements' collection.

cc @NicholasMohr

[NicholasMohr]

@pzuraq easy review, I've already approved but I don't have write access, so either giving me write access or reviewing the PR are easy steps to make this PR go away 😄

[NicholasMohr]

@pzuraq bump, only you can save us!

@pzuraq easy review, I've already approved but I don't have write access, so either giving me write access or reviewing the PR are easy steps to make this PR go away 😄

[pzuraq]

Added you as a collaborator, @twokul should already be one. Feel free to merge/release as you guys need, I'm not able to help out with this lib unfortunately at the moment, happy to transfer it if you want it to be on the Addepar github org too

[NicholasMohr]

ok thanks very much, wasn't aware @twokul was one, will let you know if we decide to transfer it!