Missing return statement at line 50?

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        String grandfatherName = reader.readLine();
        Cat catGrandfather = new Cat(grandfatherName, null, null);

        String grandmotherName = reader.readLine();
        Cat catGrandmother = new Cat(grandmotherName, null, null);

        String fatherName = reader.readLine();
        Cat catFather = new Cat(fatherName, null, catGrandfather);

        String motherName = reader.readLine();
        Cat catMother = new Cat(motherName, catGrandmother, null);

        String sonName = reader.readLine();
        Cat catSon = new Cat(sonName, catMother, catFather);

        String daughterName = reader.readLine();
        Cat catDaughter = new Cat(daughterName, catMother, catFather);

        System.out.println(catMother);
        System.out.println(catDaughter);
    }

    public static class Cat {
        private String name;
        private Cat mother;
        private Cat father;

        Cat(String name) {
            this.name = name;
        }

        Cat(String name, Cat mother, Cat father) {
            this.name = name;
            this.mother = mother;
            this.father = father;
        }

        @Override
        public String toString() {
            if (mother == null && father == null)
                return "The cat's name is " + name + ", no mother, no father ";
            else if(mother != null && father == null)
                return "The cat's name is " + name + ", " + mother.name + " is the mother, no father";
            else if(mother == null && father != null)
                return "The cat's name is " + name + ", no mother, " + father.name + " is the father";
        }
    }
}