The null pointer exception (NPE) is NOT caused by G4P it is an error in your code!

No you can't ignore the error, the only reason that the program continues is that G4P catches the null pointer exception (NPE) and prints the message rather than halt the sketch totally.

The NPE could be caused by several things and there is not enough code to determine what it might be but the most likely cause is that one of the arrays has not been created before attempting to use it - and you have so many arrays.

Try to narrow down the problem by commenting out some of the code. For instance in the code below
Test 1
Comment out lines 7-23 - if you get NPE then the letters array has not been created
Test 2
Comment out lines 9-22 - if you get NPE then the alph array has not been created

Do similar type tests for

1. void windowDraw(GWinApplet appc, GWinData data)
2. {
3.   appc.strokeWeight(typoWidth*s4cw);
4.   appc.noFill();
5.   for (int i=0 ; i < letters.length() ; i++) 
6.   {
7.     for (int j = 0; j < alph[i].lpn; j++)
8.     {
9.       appc.pushMatrix();
10.       if (!alph[i].isBezier[j]) //line
11.       {
12.         appc.translate(alph[i].sp[j].x*s4cw, alph[i].sp[j].y*s4cw);   
13.         if ( alph[i].spinning[j] || alph[i].process2stop[j] ) appc.rotate(alph[i].ra[j]);  
14.         appc.line(0, 0, alph[i].tp[j].x*s4cw, alph[i].tp[j].y*s4cw);
15.       }
16.       else //bezier
17.       {
18.         appc.translate(alph[i].sp[j].x*s4cw, alph[i].sp[j].y*s4cw);   
19.         if ( alph[i].spinning[j] || alph[i].process2stop[j] ) appc.rotate(alph[i].ra[j]);
20.         appc.bezier(0, 0, alph[i].tp1[j].x*s4cw, alph[i].tp1[j].y*s4cw, alph[i].tp2[j].x*s4cw, alph[i].tp2[j].y*s4cw, alph[i].tp[j].x*s4cw, alph[i].tp[j].y*s4cw);
21.       }
22.       appc.popMatrix();
23.     }
24.   }
25. }