'iss' can appear among the kwargs but without a value.

Author: rohe

src/idpyoidc/message/oidc/__init__.py

@@ -1016,7 +1016,7 @@ def verify(self, **kwargs):
             except KeyError:
                 pass
 
-        if "iss" in kwargs and "iss" in self:
+        if "iss" in kwargs and kwargs["iss"] and "iss" in self:
             if kwargs["iss"] != self["iss"]:
                 raise ValueError("Wrong issuer")