Reproduction steps:

1. Open "MinimalRepro" project
2. Enter Playmode
3. See Console output: "Error while downloading Asset Bundle: CRC Mismatch. Provided 49947593, calculated bca9fe0 from data. Will not load AssetBundle"

Expected Result: "UnityWebRequest" outputs Errors, even if the AssetBundle CRCs mismatch
Actual Result: "UnityWebRequest" fails to load AssetBundle, produces no Errors if AssetBundle CRCs mismatch

Reproduced with: 2019.2.0a1, 2019.1.0a14, 2018.3.3f1, 2017.4.19f1, 2017.3.2f1
Did not reproduce on: 2017.3.1p2, 2017.3.1p1, 2017.3.0f1, 2017.3.0a1

Note:
Edit path to Asset Bundle in "NewBehaviourScript.cs" script

Using "UnityWebRequest" API there's no way of knowing that it was a CRC mismatch. It can be observed that the AssetBundle download has been successful and that the load failed, but the reason for the load failure is not reported in any way.