As far as kicad is concerned a bidirectional pin can be a push pull output pin that should not be connected directly to power as it would create a short. So either your j3-8 pin has the wrong type (J would imply connector. Connectors are normally set to passive.) or kicad is right and you indeed do something that might not be the best idea.
More detail see: Electrical type of schematic symbol pins (KiCad 4 and KiCad 5)