Are you sure that this is a client problem? I guess there was a problem at resource detection, maybe an invalid server response. This is why DAVdroid uses /email@example.com/neo/://firstname.lastname@example.org/neo/. The logs you have sent do not explain how this resource has been detected.
If you have found a specific problem in DAVdroid, please let us know the exact problem, if possible with exact steps to reproduce and verbose logs of this specific problem.
Maybe it also helps to have a look at the DAVdroid source code: https://www.davdroid.com/source/