Improve input validation of isDivisible

- Use Number.isFinite() for validation
- Throw an error instead of returning a string
- Instead of returning a string, return false when divisor === 0 since no numbers are in fact divisible by 0.

Maths/IsDivisible.js

@@ -1,11 +1,11 @@
 // Checks if a number is divisible by another number.
 
-const isDivisible = (num1, num2) => {
+export const isDivisible = (num1, num2) => {
-  if (isNaN(num1) || isNaN(num2) || num1 == null || num2 == null) {
+  if (!Number.isFinite(num1) || !Number.isFinite(num2)) {
-    return 'All parameters have to be numbers'
+    throw new Error('All parameters have to be numbers')
   }
   if (num2 === 0) {
-    return 'Not possible to divide by zero'
+    return false
   }
   return num1 % num2 === 0
 }