fix(explore): catch TemplateError when validating access for query-backed permalinks

A malformed Jinja SQL template on a query-backed datasource makes
security_manager.raise_for_access() raise a raw jinja2 TemplateError via
process_jinja_sql. This propagated unwrapped through check_chart_access in the
explore permalink create/get commands and out of the API handlers, surfacing as
an opaque 500 instead of a proper 4xx.

Wrap the check_chart_access call in both commands to convert TemplateError into
a SupersetTemplateException (422), and handle that exception in the permalink API
post()/get() handlers.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/unit_tests/commands/explore/permalink/test_create.py

@@ -0,0 +1,45 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+from unittest.mock import patch
+
+import pytest
+from jinja2.exceptions import TemplateError, TemplateSyntaxError
+
+from superset.commands.explore.permalink.create import CreateExplorePermalinkCommand
+from superset.exceptions import SupersetTemplateException
+
+check_chart_access = "superset.commands.explore.permalink.create.check_chart_access"
+
+
+def test_create_permalink_malformed_jinja_template() -> None:
+    # ``check_chart_access`` funnels into ``raise_for_access`` which re-parses the
+    # query's unrendered Jinja via ``process_jinja_sql`` and can raise a raw
+    # ``TemplateError`` (e.g. an unclosed ``{% if %}``). ``TemplateSyntaxError`` is
+    # a subclass of ``TemplateError``. It must surface as a
+    # ``SupersetTemplateException`` (422), not propagate as an opaque 500.
+    assert issubclass(TemplateSyntaxError, TemplateError)
+
+    command = CreateExplorePermalinkCommand(
+        {"formData": {"datasource": "1__table", "slice_id": 1}}
+    )
+
+    with patch(
+        check_chart_access,
+        side_effect=TemplateSyntaxError("unexpected end of template", lineno=1),
+    ):
+        with pytest.raises(SupersetTemplateException):
+            command.run()