fix some tests

Author: mathurinm

skglm/solvers/base.py

@@ -110,8 +110,10 @@ def solve(self, X, y, datafit, penalty, w_init=None, Xw_init=None,
             warnings.warn(
                 "Do not pass a compiled datafit, compilation is done inside solver now")
         else:
-            datafit = compiled_clone(datafit, to_float32=X.dtype == np.float32)
-            penalty = compiled_clone(penalty)
+            if datafit is not None:
+                datafit = compiled_clone(datafit, to_float32=X.dtype == np.float32)
+            if penalty is not None:
+                penalty = compiled_clone(penalty)
             # TODO add support for bool spec in compiled_clone
             # penalty = compiled_clone(penalty, to_float32=X.dtype == np.float32)