diff --git a/panel/models/reactive_html.py b/panel/models/reactive_html.py index be6219a1ff..06fbd74238 100644 --- a/panel/models/reactive_html.py +++ b/panel/models/reactive_html.py @@ -81,6 +81,10 @@ def handle_data(self, data): elif nloops: loop = [loop for loop in (list_loop, values_loop, items_loop) if loop][0] var, obj = loop[0] + if var in self.cls.param: + raise ValueError(f'Loop variable {var} clashes with parameter name. ' + 'Ensure loop variables have a unique name. Relevant ' + f'template section:\n\n{data}') self.loop_map[var] = obj if '{% for ' in data: diff --git a/panel/reactive.py b/panel/reactive.py index 103a650611..676f48e91e 100644 --- a/panel/reactive.py +++ b/panel/reactive.py @@ -1310,7 +1310,14 @@ def _get_template(self): context[parameter] = value if parameter in self._child_names: context[f'{parameter}_names'] = self._child_names[parameter] - html = template.render(context) + try: + html = template.render(context) + except Exception as e: + raise RuntimeError( + f"{type(self).__name__} could not render " + f"template, errored with:\n\n{type(e).__name__}: {e}.\n" + f"Full template:\n\n{template_string}" + ) # Parse templated HTML parser = ReactiveHTMLParser(self.__class__, template=False)