fix: don't consider [] and [][] link references (#663)

Signed-off-by: squidfunk <martin.donath@squidfunk.com>

python/tests/unit/collectors/test_references.py

@@ -310,12 +310,6 @@ class TestLinkReferences:
                 b"id",
                 id="link-ref-with-empty-text",
             ),
-            pytest.param(
-                b"[][]",
-                b"",
-                b"",
-                id="link-ref-with-empty-text-and-id",
-            ),
             pytest.param(
                 b"[text \\]][id]",
                 b"text \\]",
@@ -472,6 +466,16 @@ class TestLinkReferences:
         refs = collect(md)
         assert len(refs) == 0
 
+    def test_no_link_ref_empty_shortcut(self) -> None:
+        md = b"[]"
+        refs = collect(md)
+        assert len(refs) == 0
+
+    def test_no_link_ref_empty_brackets(self) -> None:
+        md = b"[][]"
+        refs = collect(md)
+        assert len(refs) == 0
+
 
 # ---------------------------------------------------------------------------
 

python/zensical/collectors/references/cursor.py

@@ -424,6 +424,10 @@ def _scan_link_or_link_ref(cursor: Cursor) -> Link | LinkReference | None:
     # Consume link id
     id, end = _scan_link_id(cursor, end)
 
+    # Ignore empty shortcut references like `[]` or `[][]`.
+    if id is None and text.start == text.end:
+        return None
+
     # Advance cursor and return link reference
     cursor.advance(end - start)
     return LinkReference(