How to reproduce:
1. Open the attached "GraphView" project
2. Open the Dialogue Graph window (Graph->Dialogue Graph)
3. In the Dialogue Graph window press the "Create Node" button
4. On the newly created Node press the "New Choice" button
5. Connect the "Next" Port from the "START" Node to the "Choice 0" Port in the newly created Node

Expected results: The Graph View doesn't let you attempt to connect two output Ports together
Actual results: The Graph View lets you attempt to connect two output Ports together, errors are thrown

Reproducible with: 2019.4.9f1, 2020.1.4f1, 2020.2.0b1
Could not test with: 2018.4.27f1 because the GraphView API was not introduced

Notes:
- The same issue appears when trying to connect an input Port to another input Port
- The Ports do not get connected when trying to do so, just throws the error