Bug: nullptr arrays cause infinte recursion

[banesullivan]

If a nullptr array is present, then PyVista goes ballistic

import pyvista as pv
import vtk

earth = vtk.vtkEarthSource()
earth.SetRadius(5380)
earth.OutlineOn()
earth.Update()
continents = pv.wrap(earth.GetOutput())

# Try to access the point arrays
continents.point_arrays

Output:

---------------------------------------------------------------------------
RecursionError                            Traceback (most recent call last)
<ipython-input-15-403e4a0f4e87> in <module>
      9 
     10 # Try to access the point arrays
---> 11 continents.point_arrays

~/Documents/OpenGeoVis/Software/pyvista/pyvista/core/common.py in point_arrays(self)
    697         for i in range(narr):
    698             name = pdata.GetArrayName(i)
--> 699             self._point_arrays[name] = self._point_scalar(name)
    700 
    701         self._point_arrays.enable_callback()

~/Documents/OpenGeoVis/Software/pyvista/pyvista/core/common.py in _point_scalar(self, name)
    342         if name is None:
    343             # use active scalar array
--> 344             field, name = self.active_scalar_info
    345             if field != POINT_DATA_FIELD:
    346                 raise RuntimeError('Must specify an array to fetch.')

~/Documents/OpenGeoVis/Software/pyvista/pyvista/core/common.py in active_scalar_info(self)
     53 
     54         # rare error where scalar name isn't a valid scalar
---> 55         if name not in self.point_arrays:
     56             if name not in self.cell_arrays:
     57                 if name in self.field_arrays:

... last 3 frames repeated, from the frame below ...

~/Documents/OpenGeoVis/Software/pyvista/pyvista/core/common.py in point_arrays(self)
    697         for i in range(narr):
    698             name = pdata.GetArrayName(i)
--> 699             self._point_arrays[name] = self._point_scalar(name)
    700 
    701         self._point_arrays.enable_callback()

RecursionError: maximum recursion depth exceeded

How do I know its a nullptr issue?

print(continents.GetPointData())

vtkPointData (0x7f8a9ee428c0)
  Debug: Off
  Modified Time: 289156
  Reference Count: 2
  Registered Events: 
    Registered Observers:
      vtkObserver (0x7f8a9ee63530)
        Event: 33
        EventName: ModifiedEvent
        Command: 0x7f8a9ee90590
        Priority: 0
        Tag: 1
  Number Of Arrays: 1
  Array 0 name = nullptr
  Number Of Components: 3
  Number Of Tuples: 1028
  Copy Tuple Flags: ( 1 1 1 1 1 0 1 1 )
  Interpolate Flags: ( 1 1 1 1 1 0 0 1 )
  Pass Through Flags: ( 1 1 1 1 1 1 1 1 )
  Scalars: (none)
  Vectors: (none)
  Normals: 
    Debug: Off
    Modified Time: 289118
    Reference Count: 2
    Registered Events: (none)
    Name: (none)
    Data type: float
    Size: 3084
    MaxId: 3083
    NumberOfComponents: 3
    Information: 0x0
    Name: (none)
    Number Of Components: 3
    Number Of Tuples: 1028
    Size: 3084
    MaxId: 3083
    LookupTable: (none)
  TCoords: (none)
  Tensors: (none)
  GlobalIds: (none)
  PedigreeIds: (none)
  EdgeFlag: (none)

Note the:

...
  Number Of Arrays: 1
  Array 0 name = nullptr
...

Immediate solution incase someone else encounters this:

import vtk
earth = vtk.vtkEarthSource()
earth.SetRadius(5380)
earth.OutlineOn()
earth.Update()
foo = pv.wrap(earth.GetOutput())

# Copy the geometries only
continents = pv.PolyData()
continents.points = foo.points.copy()
continents.lines = foo.lines.copy()
del foo