You've probably experienced PS crashing with Nik and you solved it by doing the "apply filter to current layer" thing. Well, I have a different problem: Nik works OK but after using it, PS starts failing and sending Program error messages randomly. The only solution is restarting it.
I'm using the old version of Nik with CC 2018 and I wonder if this might be the problem. I was thinking about buying the new one, but I don't know if I will have the same issue.

You didn't mention your Operating System. There are compatibility issues with the Google version Nik and the current MAC OS.

The original filters from Nik became the property of Google in 2012, when Google bought Nik. They are not compatible with Windows 10, and I don't believe they're compatible with Windows 7 or recent versions of Mac OS 10.

Recently, DxO purchased the Nik collection from Google (which decided to sell them rather than make them compatible with current operating systems), and DxO has reworked the filters and made them compatible with current operating systems.

I use the old Google NIK version 1.2.11 in Windows 10 x64 + latest Photoshop CC x64, no problems here.