docs format and assertion error

docs/user/install.rst

@@ -26,11 +26,11 @@ the instructions on the relevant documentation pages:
 
 Both of these installation methods will install the required dependencies:
 
-- [numpy](https://numpy.org)
-- [astropy](https://www.astropy.org)
-- [pymc3](https://docs.pymc.io)
-- [exoplanet-core](https://github.com/exoplanet-dev/exoplanet-core)
-- [aesara-theano-fallback](https://github.com/exoplanet-dev/aesara-theano-fallback)
+- `numpy <https://numpy.org>`_
+- `astropy <https://www.astropy.org>`_
+- `pymc3 <https://docs.pymc.io>`_
+- `exoplanet-core <https://github.com/exoplanet-dev/exoplanet-core>`_
+- `aesara-theano-fallback <https://github.com/exoplanet-dev/aesara-theano-fallback>`_
 
 
 Using conda

src/exoplanet/light_curves/limb_dark.py

@@ -4,6 +4,7 @@
 
 import aesara_theano_fallback.tensor as tt
 import numpy as np
+from aesara_theano_fallback import aesara as theano
 from exoplanet_core.pymc import ops
 
 from ..citations import add_citations_to_model
@@ -47,8 +48,23 @@ def __init__(self, u1, u2=None, model=None):
                 "using a vector of limb darkening coefficients is deprecated; "
                 "use u1 and u2 directly"
             )
-            self.u1 = as_tensor_variable(u1[0])
-            self.u2 = as_tensor_variable(u1[1])
+
+            # If a vector is provided, we need to assert that it is 2D
+            msg = (
+                "only quadratic limb darkening is supported; "
+                "use `starry` for more flexibility"
+            )
+            try:
+                assert_op = theano.assert_op.Assert(msg)
+            except AttributeError:
+                assert_op = tt.opt.Assert(msg)
+            u1 = as_tensor_variable(u1)
+            u1 = assert_op(
+                u1, tt.and_(tt.eq(u1.ndim, 1), tt.eq(u1.shape[0], 2))
+            )
+
+            self.u1 = u1[0]
+            self.u2 = u1[1]
         else:
             self.u1 = as_tensor_variable(u1)
             self.u2 = as_tensor_variable(u2)

tests/light_curves_test.py

@@ -71,6 +71,11 @@ def test_vector_params():
     )(u_val)
     np.testing.assert_allclose(lc1, lc2)
 
+    with pytest.raises(AssertionError):
+        theano.function(
+            [], LimbDarkLightCurve([0.3])._compute_light_curve(b, r)
+        )()
+
 
 def test_in_transit():
     t = np.linspace(-20, 20, 1000)