0 is not a number.

[mruhlin]

If a row that I'm sorting on is 0, sorting will fail and return an error that says a number is expected.

Example:

const students = [
   {
      id: 'alice',
      mathGrade: 100,
      englishGrade: 75
   },
   {
      id: 'bob',
      mathGrade: 100,
      englishGrade: 0
   }
];

const sortOptions = {
   includeScore: true,
   mathGrade: { weight: 0.7 }},
   englishGrade: {weight: 0.3 }}
};

weightSum(students, sortOptions);

This should sort the students with Alice followed by Bob, but instead it throws an exception.
Weighted sum error: wrong data type for englishGrade. Number is expected

If I change bob's englishGrade to 1, it sorts properly.