fix: add catch for nil value

[joryirving]

Add's guard for nil value for nameOverride and fullnameOverride

Fixes #262

[itzg]

Adding the guard seems like a decent solution, but it seems like the root cause must be something like a missing root/$ context anchor somewhere. Perhaps since you can't recreate the reported issue then it's finding a needle in the haystack?

[joryirving]

Yes, without being able to reproduce it, all I have is the shared error message, and this might be a fix for it.

[itzg]

Thanks for following on this BTW.