That’s not really an error. It’s a warning, albeit one that I didn’t implement very well in Legacy Ladybug sice it gets triggered by thing other than the failure to draw the comfort polygon.
If you need a psychrometric chart that handles a much wider range of polygons with much better warnings, the psych chart in the LBT plugin is much more robust. It’s only in the development version right now but it will be in the LBT 1.2 release when we eventually release it.