This happens when accessing uv_texture data with a subscript. Create a uv texture layer on the default cube scene node and then enter this in the console:

>>> bpy.data.objects['Cube'].data.uv_textures[0]
Traceback (most recent call last):
File "<blender_console>", line 1, in <module>
RuntimeError: error getting an rna struct from a collection

This error started happening after commit r34098.