feat: add setter to dataframe to handle missing text_keys (#6785)

* update the templates and add error handling

* [autofix.ci] apply automated fixes

* updated changes

* update to template from main

* Update split_text.py

* Add validation for text key in DataFrame setter

---------

Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Gabriel Luiz Freitas Almeida <gabriel@langflow.org>

src/backend/base/langflow/schema/dataframe.py

@@ -72,6 +72,9 @@ class DataFrame(pandas_DataFrame):
 
     @text_key.setter
     def text_key(self, value: str) -> None:
+        if value not in self.columns:
+            msg = f"Text key '{value}' not found in DataFrame columns"
+            raise ValueError(msg)
         self._text_key = value
 
     @property