I don’t understand how to solve – Warning: Trying to access array offset on value of type null in [duplicate]

Hi guys can you help me with this error:

Warning: Trying to access array offset on value of type null in C:xampphtdocsinnovatiowh_localgestioneutilFunction.php on line 269

Warning: Trying to access array offset on value of type null in C:xampphtdocsinnovatiowh_localgestioneutilFunction.php on line 270

Warning: Trying to access array offset on value of type null in C:xampphtdocsinnovatiowh_localgestioneutilFunction.php on line 271

Thank you in advance