Add error handling for zero denominator in isProperFraction function

Author: Payman IB

Sprint-3/1-implement-and-rewrite-tests/implement/2-is-proper-fraction.js

@@ -8,12 +8,11 @@
 // write one test at a time, and make it pass, build your solution up methodically
 
 function isProperFraction(numerator, denominator) {
-  if (Math.abs(numerator) < Math.abs(denominator)) {
-    return true;
-  }
-  else if (numerator >= denominator) {
-    return false;
+  if (denominator === 0) {
+    throw new Error("Denominator cannot be zero");
   }
+
+  return Math.abs(numerator) < Math.abs(denominator);
 }
 
 // The line below allows us to load the isProperFraction function into tests in other files.