Improved resilience of privacy plugin

material/plugins/privacy/plugin.py

@@ -33,6 +33,7 @@ from concurrent.futures import Future, ThreadPoolExecutor, wait
 from hashlib import sha1
 from mkdocs.config.config_options import ExtraScriptValue
 from mkdocs.config.defaults import MkDocsConfig
+from mkdocs.exceptions import PluginError
 from mkdocs.plugins import BasePlugin, event_priority
 from mkdocs.structure.files import File, Files
 from mkdocs.utils import is_error_template
@@ -241,10 +242,19 @@ class PrivacyPlugin(BasePlugin[PrivacyConfig]):
         parser.feed(fragment)
         parser.close()
 
-        # Return element
-        assert isinstance(parser.result, Element)
+        # Check parse result and return element
+        if isinstance(parser.result, Element):
             return parser.result
 
+        # Otherwise, raise a plugin error - if the author accidentally used
+        # invalid HTML inside of the tag, e.g., forget a opening or closing
+        # quote, we need to catch this here, as we're using pretty basic
+        # regular expression based extraction
+        raise PluginError(
+            f"Could not parse due to possible syntax error in HTML: \n\n"
+            + fragment
+        )
+
     # Parse and extract all external assets from a media file using a preset
     # regular expression, and return all URLs found.
     def _parse_media(self, initiator: File) -> list[URL]:

src/plugins/privacy/plugin.py

@@ -33,6 +33,7 @@ from concurrent.futures import Future, ThreadPoolExecutor, wait
 from hashlib import sha1
 from mkdocs.config.config_options import ExtraScriptValue
 from mkdocs.config.defaults import MkDocsConfig
+from mkdocs.exceptions import PluginError
 from mkdocs.plugins import BasePlugin, event_priority
 from mkdocs.structure.files import File, Files
 from mkdocs.utils import is_error_template
@@ -241,10 +242,19 @@ class PrivacyPlugin(BasePlugin[PrivacyConfig]):
         parser.feed(fragment)
         parser.close()
 
-        # Return element
-        assert isinstance(parser.result, Element)
+        # Check parse result and return element
+        if isinstance(parser.result, Element):
             return parser.result
 
+        # Otherwise, raise a plugin error - if the author accidentally used
+        # invalid HTML inside of the tag, e.g., forget a opening or closing
+        # quote, we need to catch this here, as we're using pretty basic
+        # regular expression based extraction
+        raise PluginError(
+            f"Could not parse due to possible syntax error in HTML: \n\n"
+            + fragment
+        )
+
     # Parse and extract all external assets from a media file using a preset
     # regular expression, and return all URLs found.
     def _parse_media(self, initiator: File) -> list[URL]: