Fatal error: Uncaught TypeError: Argument 1 passed to Mail::mail_signup_ins() must be of the type string, null given, called in /home/ruijuku/rui.ne.jp/public_html/shizen/adventure/signup/complete.php on line 36 and defined in /home/ruijuku/rui.ne.jp/public_html/shizen/adventure/inc/Mail.inc:7 Stack trace: #0 /home/ruijuku/rui.ne.jp/public_html/shizen/adventure/signup/complete.php(36): Mail::mail_signup_ins(NULL, NULL, NULL) #1 {main} thrown in /home/ruijuku/rui.ne.jp/public_html/shizen/adventure/inc/Mail.inc on line 7