Error: Nodes Cannot be Empty
This edition of rare and silly errors is brought to you by LINQ:
The offending line was where Sitecore ContentSearch's
GetQueryable was called:
Knowing that the problem wasn't actually there, I inspected the
query that was built prior to calling
Given that the error message said
nodes are empty, the smoking gun was the "array contains x" operation.
But it worked on all environments, except for one! Turns out, it's because the
legacyTargets array WAS empty.
This was due to a content delta between environments in which some items that were expected to be there... Weren't.
This situation is such a classic one in Sitecore. When fetching any information related to items, there will always be a chance that information is missing or different than you were expecting. Defensive programming pays dividends.
Keep on building,