I have this:

var query = from g in root.Groups
            from r in g.Rules
            from c in r.Conditions
            from a in c.Actions
            where g.Rules != null
            where r.Conditions != null
            where c.Actions != null
            where a.ActionID == ActionId
            select a;

List<RuleAction> items = query.ToList();
RetVal = items[0];

It fails on the last line with "Object reference not set to an instance of an object" because the query returned no results.

How do I test for this before attempting to convert the results to a list?