$ ipython mytest.py
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/Users/ajfriend/Dropbox/work/cvxpy/mytest.py in <module>()
      7
      8 prob = cvx.Problem(cvx.Maximize(cvx.sum_entries(g) + y), [0 <= x, x <= 1, y <= 2])
----> 9 prob.solve()

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/problems/problem.pyc in solve(self, *args, **kwargs)
    154             return func(self, *args, **kwargs)
    155         else:
--> 156             return self._solve(*args, **kwargs)
    157
    158     @classmethod

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/problems/problem.pyc in _solve(self, solver, ignore_dcp, warm_start, verbose, **kwargs)
    224                 raise Exception("Problem does not follow DCP rules.")
    225
--> 226         objective, constraints = self.canonicalize()
    227         # Choose a solver/check the chosen solver.
    228         if solver is None:

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/problems/problem.pyc in canonicalize(self)
    101         """
    102         canon_constr = []
--> 103         obj, constr = self.objective.canonical_form
    104         canon_constr += constr
    105

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/performance_utils.pyc in _lazyprop(self)
     36         """
     37         if not hasattr(self, attr_name):
---> 38             setattr(self, attr_name, func(self))
     39         return getattr(self, attr_name)
     40     return _lazyprop

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/canonical.pyc in canonical_form(self)
     44             A tuple of (affine expression, [constraints]).
     45         """
---> 46         return self.canonicalize()
     47
     48     @abc.abstractmethod

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/problems/objective.pyc in canonicalize(self)
     82         """Negates the target expression's objective.
     83         """
---> 84         obj, constraints = super(Maximize, self).canonicalize()
     85         return (lu.neg_expr(obj), constraints)
     86

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/problems/objective.pyc in canonicalize(self)
     44         """Pass on the target expression's objective and constraints.
     45         """
---> 46         return self._expr.canonical_form
     47
     48     def variables(self):

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/performance_utils.pyc in _lazyprop(self)
     36         """
     37         if not hasattr(self, attr_name):
---> 38             setattr(self, attr_name, func(self))
     39         return getattr(self, attr_name)
     40     return _lazyprop

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/canonical.pyc in canonical_form(self)
     44             A tuple of (affine expression, [constraints]).
     45         """
---> 46         return self.canonicalize()
     47
     48     @abc.abstractmethod

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/atoms/atom.pyc in canonicalize(self)
    114             constraints = []
    115             for arg in self.args:
--> 116                 obj, constr = arg.canonical_form
    117                 arg_objs.append(obj)
    118                 constraints += constr

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/performance_utils.pyc in _lazyprop(self)
     36         """
     37         if not hasattr(self, attr_name):
---> 38             setattr(self, attr_name, func(self))
     39         return getattr(self, attr_name)
     40     return _lazyprop

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/utilities/canonical.pyc in canonical_form(self)
     44             A tuple of (affine expression, [constraints]).
     45         """
---> 46         return self.canonicalize()
     47
     48     @abc.abstractmethod

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/atoms/atom.pyc in canonicalize(self)
    109             # Non-parameterized expressions are evaluated immediately.
    110             else:
--> 111                 return Constant(self.value).canonical_form
    112         else:
    113             arg_objs = []

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/expressions/constants/constant.pyc in __init__(self, value)
     34             self._sparse = True
     35         else:
---> 36             self._value = intf.DEFAULT_INTERFACE.const_to_matrix(value)
     37             self._sparse = False
     38         # Set DCP attributes.

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/interface/base_matrix_interface.pyc in new_converter(self, value, convert_scalars)
     47     def scalar_const(converter):
     48         def new_converter(self, value, convert_scalars=False):
---> 49             if not convert_scalars and cvxpy.interface.matrix_utilities.is_scalar(value):
     50                 return cvxpy.interface.matrix_utilities.scalar_value(value)
     51             else:

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/interface/matrix_utilities.pyc in is_scalar(constant)
     76 # Is the constant a scalar?
     77 def is_scalar(constant):
---> 78     return size(constant) == (1, 1)
     79
     80 def from_2D_to_1D(constant):

/Users/ajfriend/Dropbox/work/cvxpy/cvxpy/interface/matrix_utilities.pyc in size(constant)
     68         return INTERFACES[sp.csc_matrix].size(constant)
     69     else:
---> 70         raise TypeError("%s is not a valid type for a Constant value." % type(constant))
     71
     72 # Is the constant a column vector?

TypeError: <type 'NoneType'> is not a valid type for a Constant value.