test: add test case and fix typos in comment

Author: kenjis

tests/system/Models/DeleteModelTest.php

@@ -148,8 +148,8 @@ public function testOnlyDeleted(): void
     }
 
     /**
-     * If where condition is set, beyond the value was empty (0,'', NULL, etc.),
-     * Exception should not be thrown because condition was explicity set
+     * If where condition is set, beyond the value was empty (0, '', NULL, etc.),
+     * Exception should not be thrown because condition was explicitly set
      *
      * @dataProvider emptyPkValues
      *
@@ -203,6 +203,7 @@ public static function emptyPkValues(): iterable
             [0],
             [null],
             ['0'],
+            [''],
         ];
     }