I have a file with a list of numbers I need to add. I load it using loadStrings(), and then I want to convert each line of String array to an int. I wonder why I get a NullPointerExeption error?

2. String lines[] = loadStrings("nums.txt");
3. int sum;
4. int converted;
5. int i = 1;
6. 
   
7. void draw() {
8.   if (i<100) {
9.     sum=sum+int(lines[i]);
10.     println(sum);
11.     i++;
12.   }
13. }