Fix get_def_dict to return value if no sidecar

Author: IanCa

hed/models/tabular_input.py

@@ -67,7 +67,7 @@ def get_def_dict(self, hed_schema, extra_def_dicts=None):
         if self._sidecar:
             return self._sidecar.get_def_dict(hed_schema, extra_def_dicts)
         else:
-            super().get_def_dict(hed_schema, extra_def_dicts)
+            return super().get_def_dict(hed_schema, extra_def_dicts)
 
     def get_column_refs(self):
         """ Returns a list of column refs for this file.