adjust model output if last node is removed

Author: JanFSchulte

hls4ml/model/graph.py

@@ -565,6 +565,9 @@ def remove_node(self, node, rewire=True):
                     if outputs[0] == nxt_inp:
                         next_node.inputs[i] = inputs[0]
 
+        if node.outputs[0] == self.outputs[0]:
+            prev_node = node.get_input_node(node.inputs[0])
+            self.outputs[0] = prev_node.outputs[0]
         del self.output_vars[node.outputs[0]]
         del self.graph[node.name]