If you have used the Dendro Volume to Mesh component you may have gotten an “Invalid Mesh” on complex outputs. This appears to be a result of mesh vertices being generated out of Dendro that are closer than the minimum tolerances defined in Rhino (possible floating point rounding error).
Saw this mentioned on another post but a quick solution that seems to solve this issue is to use the Pufferfish Rebuild Mesh component with “Merge Vertices” enabled. This fix is pretty computationally efficient compared to other options like using Align Vertices.