"extract" function exists in "basic.js" and "basic2.js" files
"basic.js" line : 448
"basic2.js" line 149
They overwrite "extract" node.
Try commenting out "extract" function in "basic2.js" file as well.
Or just manually modify them.
I've changed this line:

this.local = {pointarray:["X", "X", "Y", "Z", "rX", "rY", "rZ", "Scale"], numarray:["Min", "Min", "Max", "Average"]};

To this:

this.local = {pointarray:["X", "X", "Y", "Z", "rX", "rY", "rZ", "Scale"], numarray:["Min", "Min", "Max", "Average", "Sum"]};

and added this line:

case 4:	o = 0; for ( i = 0; i<inp.length; i++) o += inp[i]; break;

after this line:

case 3:	o = 0; for ( i = 0; i<inp.length; i++) o += inp[i];	o /= inp.length; break;