Hmm … I think I have investigated this before, but I may give it another shot. The stack trace (that we don’t show) is not useful, as it just points to some point in Go’s framework (and not the line in the template). But I have seen some talk about “template nils” suggesting that we could maybe possibly do better. We should at least talk to the Go people about it and see if there are something we can do. I got pretty good training tracking down these situations, but I can imagine the pain of people new to Hugo.
Create an issue, but I will not promise anything …