Fixed NPE when there are no definitions set

Commands/InterviewTemplateCommands.cs

@@ -136,7 +136,7 @@ public class InterviewTemplateCommands
             List<string> errors = [];
             List<string> warnings = [];
             template.interview.Validate(ref errors, ref warnings, "interview", template.definitions);
-            foreach (KeyValuePair<string, InterviewStep> definition in template.definitions)
+            foreach (KeyValuePair<string, InterviewStep> definition in template.definitions ?? [])
             {
                 definition.Value.Validate(ref errors, ref warnings, "definitions." + definition.Key, template.definitions);
             }

Interviews/interview_template.schema.json

@@ -223,6 +223,6 @@
       }
     }
   },
-  "required": [ "category-id", "interview" ],
+  "required": [ "category-id", "interview", "definitions" ],
   "unevaluatedProperties": false
 }