return null first

api-v13/app/Services/PaliTextService.php

@@ -34,12 +34,11 @@ class PaliTextService
             ->where('paragraph', '<=', $para)
             ->where('level', 1)
             ->orderBy('paragraph', 'asc')->first();
-        if ($paragraph) {
-            return $paragraph;
-        } else {
-            Log::error('not found book ', ['book' => $book, 'para' => $para]);
+        if (!$paragraph) {
+            Log::warning('not found book ', ['book' => $book, 'para' => $para]);
             return null;
         }
+        return $paragraph;
     }
     public function getParaCategoryTags(int $book, int $para): array
     {