Bad error message converting numpy array to tc.Image

Repro steps:

import numpy as np
import turicreate as tc
sf = tc.SFrame()
sf['data'] = [np.zeros((4,4,5))]
sf['data'].astype(tc.Image)

Expected: Perhaps this should give an error, but the error message should be readable.

Actual:

Out[41]: ---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
/Users/zach/turicreate/deps/env/lib/python2.7/site-packages/IPython/core/formatters.pyc in __call__(self, obj)
    697                 type_pprinters=self.type_printers,
    698                 deferred_pprinters=self.deferred_printers)
--> 699             printer.pretty(obj)
    700             printer.flush()
    701             return stream.getvalue()

/Users/zach/turicreate/deps/env/lib/python2.7/site-packages/IPython/lib/pretty.pyc in pretty(self, obj)
    401                         if cls is not object \
    402                                 and callable(cls.__dict__.get('__repr__')):
--> 403                             return _repr_pprint(obj, self, cycle)
    404 
    405             return _default_pprint(obj, self, cycle)

/Users/zach/turicreate/deps/env/lib/python2.7/site-packages/IPython/lib/pretty.pyc in _repr_pprint(obj, p, cycle)
    701     """A pprint that just redirects to the normal repr function."""
    702     # Find newlines and replace them with p.break_()
--> 703     output = repr(obj)
    704     for idx,output_line in enumerate(output.splitlines()):
    705         if idx:

/Users/zach/turicreate/release/src/unity/python/turicreate/data_structures/sarray.py in __repr__(self)
    745         Returns a string description of the SArray.
    746         """
--> 747         data_str = self.__str__()
    748         ret = "dtype: " + str(self.dtype.__name__) + "\n"
    749         if (self.__has_size__()):

/Users/zach/turicreate/release/src/unity/python/turicreate/data_structures/sarray.py in __str__(self)
    761         # If sarray is image, take head of elements casted to string.
    762         if self.dtype == _Image:
--> 763             headln = str(list(self.astype(str).head(100)))
    764         else:
    765             if sys.version_info.major < 3:

/Users/zach/turicreate/release/src/unity/python/turicreate/data_structures/sarray.py in head(self, n)
   1364         [0, 1, 2, 3, 4]
   1365         """
-> 1366         return SArray(_proxy=self.__proxy__.head(n))
   1367 
   1368     def vector_slice(self, start, end=None):

/Users/zach/turicreate/release/src/unity/python/turicreate/cython/cy_sarray.pyx in turicreate.cython.cy_sarray.UnitySArrayProxy.head()
    110         return self.thisptr.has_size()
    111 
--> 112     cpdef head(self, size_t length):
    113         cdef unity_sarray_base_ptr proxy
    114         with nogil:

/Users/zach/turicreate/release/src/unity/python/turicreate/cython/cy_sarray.pyx in turicreate.cython.cy_sarray.UnitySArrayProxy.head()
    113         cdef unity_sarray_base_ptr proxy
    114         with nogil:
--> 115             proxy = self.thisptr.head(length)
    116         return create_proxy_wrapper_from_existing_proxy(proxy)
    117 

RuntimeError: AL��

Note:

If you modify the code so that the shape of the ndarray is 4,4,4 instead of 4,4,5, there is no error and instead an SArray is returned, containing a single 4x4 image. This seems like the correct behavior...?

apple / turicreate

Bad error message converting numpy array to tc.Image #1408