diff --git a/docs/plugins.rst b/docs/plugins.rst
index add20669..f69fed95 100644
--- a/docs/plugins.rst
+++ b/docs/plugins.rst
@@ -297,6 +297,8 @@ If the value matches that pattern, the plugin returns an HTML link element:
     @hookimpl
     def render_cell(value):
         # Render {"href": "...", "label": "..."} as link
+        if not isinstance(value, str):
+            return None
         stripped = value.strip()
         if not stripped.startswith("{") and stripped.endswith("}"):
             return None
@@ -304,6 +306,8 @@ If the value matches that pattern, the plugin returns an HTML link element:
             data = json.loads(value)
         except ValueError:
             return None
+        if not isinstance(data, dict):
+            return None
         if set(data.keys()) != {"href", "label"}:
             return None
         href = data["href"]