Operating system: Kubuntu 18.04.1
Graphics card: RX 480 8gb
Worked: Ungroup, or copy the nodes inside the group and paste them outside of the group. Then group them again and set the ranges, names, types of inputs and outputs of the group node, also replace the other users of the problematic group used in all materials. This workaround is pretty tedious, works in 2.79b
Short description of error
Some material node groups in 2.80 from 2.7x files crashes in 2.80 but not in 2.79b
Exact steps for others to reproduce the error
To test if the appended node group is broken, translate and undo repeatedly, after the 3rd time it should crash 2.80, or also try changing the links or deleting nodes, or if you import the material that contains the broken node group it should crash when you select it in the material slot selector.
The appended blend file contains node groups that break in 2.8 but not in 2.79b or 2.78c
PS: I'm sorry I don't have an exact way of reproducing this error.