fix: Handle extraction patterns that return None (#26)

Reviewed-on: #26
Co-authored-by: Glen Whitney <glen@studioinfinity.org>
Co-committed-by: Glen Whitney <glen@studioinfinity.org>

mkdocs_semiliterate/plugin.py

@@ -156,6 +156,8 @@ is checked for `{! ... !}`.
            and handling inclusion syntax.
         """
         line = extraction_pattern.replace_line(line)
+        if line is None:
+            return
         include_match = StreamInclusion.include_open.search(line)
         if not include_match:
             self.output_stream.write(line)

setup.cfg

@@ -1,6 +1,6 @@
 [metadata]
 name = mkdocs-semiliterate
-version = 0.8.0
+version = 0.8.1
 description = Extension of mkdocs-simple-plugin adding easy content inclusion
 long_description = file: README.md
 long_description_content_type = text/markdown