fix port delete

Author: ArnoChenFx

NodeGraphQt/base/node.py

@@ -884,6 +884,7 @@ def delete_input(self, port):
         self._inputs.remove(port)
         self._model.inputs.pop(port.name())
         self._view.delete_input(port.view)
+        port.model.node = None
         self.draw()
 
     def delete_output(self, port):
@@ -900,6 +901,7 @@ def delete_output(self, port):
         self._outputs.remove(port)
         self._model.outputs.pop(port.name())
         self._view.delete_output(port.view)
+        port.model.node = None
         self.draw()
 
     def set_ports(self, port_data):
@@ -910,8 +912,12 @@ def set_ports(self, port_data):
             port_data(dict): {'input_ports':[{'name':...,'multi_connection':...,'display_name':...,'data_type':...}, ...],
             "                 'output_ports':[{'name':...,'multi_connection':...,'display_name':...,'data_type':...}, ...]}
         """
-        [self._view.delete_input(port.view) for port in self._inputs]
-        [self._view.delete_output(port.view) for port in self._outputs]
+        for port in self._inputs:
+            self._view.delete_input(port.view)
+            port.model.node = None
+        for port in self._outputs:
+            self._view.delete_output(port.view)
+            port.model.node = None
         self._inputs = []
         self._outputs = []
         self._model.outputs = {}