Eh, what an ignorant point of view, sorry to be blunt.

Tests and assertions can only protect you from bugs you already assumed can happen, and they can protect you from the same bug happening again under the exactly same circumstances. They are completely useless for unexpected, unreproducible bugs which only happen when the stars align the right way.

Logging is a bit more useful but has some of the same problems, you only know what to log when you know what bugs to expect.