Fix assertion for reaction term in Transport

src/bvpy/templates/vforms/transport.py

@@ -77,7 +77,6 @@ class TransportForm(AbstractVform):
         else:
             self._velocity = velocity
 
-        assert isinstance(self._reaction, FunctionType)
         self._reaction = reaction
 
     def construct_form(self, u, v, sol):
@@ -91,7 +90,7 @@ class TransportForm(AbstractVform):
 
         #If reaction it's a non-linear problem
         else:
-
+            assert isinstance(self._reaction, FunctionType)
             self.lhs = self._diffusivity*dot(grad(sol), grad(v))*self.dx - \
                        self._source*v*self.ds - \
                        self._diffusivity*self._neumann_term(v) - \