Log : PHPExcel_Reader_Excel2007 Trying to access array offset on value of type null Line 1117

Find the line of the error at the library file, in my case was some array that should not be null $attributes[$t] I've change it.

if ($attributes['t'] == 'array') { //from this
if (isset($attributes['t']) && $attributes['t'] == 'array') { //to this

the error dissapeared.