findMaxNumber

Write a function findMaxNumber that takes an array of numbers as input and returns the largest number in the array. If the array is empty, return null.

Example Inputs & Outputs

findMaxNumber([1, 2, 3, 4, 5])       // → 5  
findMaxNumber([-10, -20, -3, -1])   // → -1  
findMaxNumber([42])                // → 42  
findMaxNumber([])                  // → null  
findMaxNumber([100, 100, 100])     // → 100  

Constraints & Edge Cases

• Input is always an array.
• Array can include positive, negative, and zero values.
• Array can be empty — in that case, return null.
• Array may include duplicate values.
• Must not mutate the original array.