documentation/doxygen: add a human-readable assert here.

diff --git a/documentation/doxygen.py b/documentation/doxygen.py
index 2276e4120cf94161776c5c1cc4d60ef24d5b93cf..d8b2df2284e834abe67e432da5e4350bfa624aca 100755 (executable)
--- a/documentation/doxygen.py
+++ b/documentation/doxygen.py
@@ -2334,6 +2334,7 @@ def postprocess_state(state: State):
     # Resolve navbar links that are just an ID
     def resolve_link(html, title, url, id):
         if not html and not title and not url:
+            assert id in state.compounds, "Navbar references {} which wasn't found".format(id)
             found = state.compounds[id]
             title, url = found.name, found.url
         return html, title, url, id