Can anyone help me out? Error: Your setter method is returning the wrong value

class Student {
    constructor(gpa, credits) {
        this.gpa = gpa;
        this.credits = credits;
    }

    stringGPA() {
        return this.gpa.toString();
    }

    get level() {
        if (this.credits > 90) {
            this.major = 'Senior';
            return 'Senior';
        } else if (this.credits > 60) {
            this.major = 'Junior';
            return 'Junior';
        } else if (this.credits > 30) {
            this.major = 'None';
            return 'Sophomore';
        } else {
            this.major = 'None';
            return 'Freshman';
        }
    }

    set major(value) {
      this._major = value;
    }
}

var student = new Student(3.9, 60);