Allows strings if layout is a list

Author: leeagustin

dash/_validate.py

@@ -439,11 +439,13 @@ def _validate_id(comp):
 
     if isinstance(layout_value, (list, tuple)):
         for component in layout_value:
+            if isinstance(component, (str,)):
+                continue
             if isinstance(component, (Component,)):
                 _validate(component)
             else:
                 raise exceptions.NoLayoutException(
-                    "List of components as layout must be a list of components only."
+                    "List of components as layout must be a list of strings and components only."
                 )
     else:
         _validate(layout_value)