Fatal error: Uncaught TypeError: strtotime(): Argument #2 ($baseTimestamp) must be of type ?int, string given in /in/MSB1q:3
Stack trace:
#0 /in/MSB1q(3): strtotime('+1 month', '2013-01-31')
#1 {main}
thrown in /in/MSB1q on line 3
Process exited with code 255.