The variable $trace seems to be defined by a foreach iteration on line 40. Are you sure the iterator is never empty, otherwise this variable is not defined?
It seems like you are relying on a variable being defined by an iteration:
foreach($aas$b){}// $b is defined here only if $a has elements, for example if $a is array()// then $b would not be defined here. To avoid that, we recommend to set a// default value for $b.// Better$b=0;// or whatever default makes sense in your contextforeach($aas$b){}// $b is now guaranteed to be defined here.
It seems like you are relying on a variable being defined by an iteration: