Simplification

nifty5/operators/linear_operator.py

@@ -263,8 +263,6 @@ class LinearOperator(Operator):
             s = "The operator's and field's domains don't match."
             from ..domain_tuple import DomainTuple
             from ..multi_domain import MultiDomain
-            if not isinstance(self._dom(mode),
-                              [DomainTuple, MultiDomain]) or isinstance(
-                                  x.domain, [DomainTuple, MultiDomain]):
-                s += " One of the domains is neither a `DomainTuple` nor a `MultiDomain`."
+            if not isinstance(self._dom(mode), [DomainTuple, MultiDomain]):
+                s += " Your operator's domain is neither a `DomainTuple` nor a `MultiDomain`."
             raise ValueError(s)

nifty5/operators/operator.py

@@ -70,10 +70,8 @@ class Operator(NiftyMetaBase()):
             s = "The operator's and field's domains don't match."
             from ..domain_tuple import DomainTuple
             from ..multi_domain import MultiDomain
-            if not isinstance(self._dom(mode),
-                              [DomainTuple, MultiDomain]) or isinstance(
-                                  x.domain, [DomainTuple, MultiDomain]):
-                s += " One of the domains is neither a `DomainTuple` nor a `MultiDomain`."
+            if not isinstance(self._dom(mode), [DomainTuple, MultiDomain]):
+                s += " Your operator's domain is neither a `DomainTuple` nor a `MultiDomain`."
             raise ValueError(s)
 
     def __call__(self, x):