error on invalid hours argument

index.js

@@ -206,6 +206,9 @@ class App {
     async update(sheetname, startDate, endDate, hours) { // set values in sheet
         console.log("Setting data in", sheetname)
         hours = +hours
+        if (isNaN(hours)) {
+            throw "hours argument not a float or int"
+        }
         const values = {
             regular: Math.min(hours, 80),
             overwork: Math.max(0, hours-80),