fix: throws InvalidScopeError if the FieldData for the scope is None

xblock/field_data.py

@@ -148,7 +148,12 @@ def _field_data(self, block, name):
         if scope not in self._scope_mappings:
             raise InvalidScopeError(scope)
 
-        return self._scope_mappings[scope]
+        scope_mapping = self._scope_mappings[scope]
+
+        if scope_mapping is None:
+            raise InvalidScopeError(scope)
+
+        return scope_mapping
 
     def get(self, block, name):
         return self._field_data(block, name).get(block, name)

xblock/test/test_field_data.py

@@ -40,6 +40,11 @@ def setup_method(self):
             Scope.content: self.content,
             Scope.settings: self.settings
         })
+        self.split_empty = SplitFieldData({
+            Scope.content: self.content,
+            Scope.settings: self.settings,
+            Scope.user_state: None,
+        })
         self.runtime = TestRuntime(services={'field-data': self.split})
         self.block = TestingBlock(
             runtime=self.runtime,
@@ -76,6 +81,10 @@ def test_invalid_scope(self):
         with pytest.raises(InvalidScopeError):
             self.split.get(self.block, 'user_state')
 
+    def test_empty_scope(self):
+        with pytest.raises(InvalidScopeError):
+            self.split_empty.get(self.block, 'user_state')
+
     def test_default(self):
         self.split.default(self.block, 'content')
         self.content.default.assert_called_once_with(self.block, 'content')