Update tests for onError callback to check usual logging does not happen

[romaricpascal]

What

Address this comment in its own PR.

Why

We're currently testing that the callback is executed, but not that the initial logging no longer happens.
This should also simplify the tests a little as we wouldn't need the spy to log so we can then check that console.log was called.

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

Tests for the error callback using console.log in the spy now:

• Check that the spy's been called with the right shape of arguments
• Check that no logging happened