conf/output: friendly error message on bad configuration

Ticket: 7611

Instead of segfault

output.types expects a sequence of one-key mappings, instead
of directly a mapping

src/runmodes.c

@@ -669,6 +669,9 @@ static void RunModeInitializeEveOutput(
     if (types == NULL) {
         return;
     }
+    if (!SCConfNodeIsSequence(types)) {
+        FatalError("output types should be a sequence");
+    }
 
     SCConfNode *type = NULL;
     TAILQ_FOREACH(type, &types->head, next) {