Add more panic() calls for invalid conditions

repository/index.go

@@ -215,6 +215,10 @@ func (idx *Index) generatePackList(selectFn func(indexEntry) bool) ([]*packJSON,
 	packs := make(map[backend.ID]*packJSON)
 
 	for id, blob := range idx.pack {
+		if blob.packID == nil {
+			panic("nil pack id")
+		}
+
 		if selectFn != nil && !selectFn(blob) {
 			continue
 		}