fixed wrong model init

test/test_transitions.jl

@@ -8,7 +8,7 @@ julia_test_file = "test/traces/julia.csv"
     )
 
     transient_node = add_submodel!(top, :transient, MockNode;
-        inbox=(; in=Int[]), ta=0.0, forward=true
+        inbox=(; in=Int[]), out_ports=(; out=Int), ta=0.0, forward=true
     )
     connect!(top, sender_ref.out, transient_node.in)