fix: a:c:l command unset reference to prevent type-changing side effect

src/Command/CreateProductionCommand.php

@@ -133,6 +133,8 @@ class CreateProductionCommand extends Command
                 foreach (self::extractKanji($term->getKanji()) as $kanji) {
                     $knownKanji[$kanji] = 0;
                 }
+                // Please put me into a function
+                unset($term); // Prevent things being reassigned
             }
         }
         printf(" OK (%d)\n", count($knownKanji));