Html::button() type is `button` by default

framework/helpers/BaseHtml.php

@@ -425,6 +425,9 @@ class BaseHtml
      */
     public static function button($content = 'Button', $options = [])
     {
+        if (!isset($options['type'])) {
+            $options['type'] = 'button';
+        }
         return static::tag('button', $content, $options);
     }