[String] Fix Notice when argument is empty string

Author: moldman

Inflector/EnglishInflector.php

@@ -305,6 +305,7 @@ final class EnglishInflector implements InflectorInterface
      * A list of words which should not be inflected, reversed.
      */
     private static $uninflected = [
+        '',
         'atad',
         'reed',
         'kcabdeef',

Tests/EnglishInflectorTest.php

@@ -306,4 +306,16 @@ public function testPluralize(string $singular, $plural)
     {
         $this->assertSame(\is_array($plural) ? $plural : [$plural], (new EnglishInflector())->pluralize($singular));
     }
+
+    public function testPluralizeEmptyString()
+    {
+        $plural = (new EnglishInflector())->pluralize('');
+        $this->assertSame([''], $plural);
+    }
+
+    public function testSingularizeEmptyString()
+    {
+        $singular = (new EnglishInflector())->singularize('');
+        $this->assertSame([''], $singular);
+    }
 }