This is only happening when background resource processing is turned on in the settings, and once it starts happening in a savegame, it doesn't go away until I go back to Space Center, go into Settings, and turn off EC background processing. Possibly related is that even when I leave fuel cells turned on, I still run out of EC on background craft and have to visit them to get them to "catch up" even though I have background processing turned on. This is using CKAN latest version 0.17.0.0. I run more than a few mods, but it looks like another case where a mod might want to do some null checks on parameters passed and received, not sure

Debian 5.10.9-1, KSP 1.11.2

EXC 14:36:00.190] NullReferenceException: Object reference not set to an instance of an object
BackgroundResources.ModuleResourceConverter.ProcessHandler () (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
BackgroundResources.UnloadedResources.ProcessInterestedModules (BackgroundResources.InterestedVessel vessel) (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
BackgroundResources.UnloadedResources.FixedUpdate () (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
UnityEngine.DebugLogHandler:LogException(Exception, Object)
ModuleManager.UnityLogHandle.InterceptLogHandler:LogException(Exception, Object)
UnityEngine.Debug:CallOverridenDebugHandler(Exception, Object)
[EXC 14:36:00.546] NullReferenceException: Object reference not set to an instance of an object
BackgroundResources.ModuleResourceConverter.ProcessHandler () (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
BackgroundResources.UnloadedResources.ProcessInterestedModules (BackgroundResources.InterestedVessel vessel) (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
BackgroundResources.UnloadedResources.FixedUpdate () (at <6f330a802bcb4bcf85306a33c6e76aa8>:0)
UnityEngine.DebugLogHandler:LogException(Exception, Object)
ModuleManager.UnityLogHandle.InterceptLogHandler:LogException(Exception, Object)
UnityEngine.Debug:CallOverridenDebugHandler(Exception, Object)
KSP.log

Full KSP.log attached

this is now fixed in V0.18.0