fix: stem_token/stem_tokens — try/except sur crash snowballstemmer (IndexError sur tokens exotiques)

backend/search.py

@@ -44,13 +44,22 @@ def _get_stemmer():
 
 def stem_token(token: str) -> str:
     """Reduce a word to its French stem (e.g. 'mangeons' → 'mang')."""
+    try:
         return _get_stemmer().stemWord(token)
+    except Exception:
+        return token  # fallback: keep original token if stemmer crashes
 
 
 def stem_tokens(tokens: list[str] | set[str]) -> set[str]:
     """Return the set of unique stems for a list of tokens."""
-    s = _get_stemmer()
-    return {s.stemWord(t) for t in tokens}
+    result = set()
+    for t in tokens:
+        try:
+            stemmed = stem_token(t)
+        except Exception:
+            stemmed = t
+        result.add(stemmed)
+    return result
 
 
 # ---------------------------------------------------------------------------