How can PHP developers ensure that their code is properly handling different types of input data, such as arrays or single values?

PHP developers can ensure their code properly handles different types of input data by using conditional statements to check the type of the input before processing it. They can use functions like `is_array()` or `is_scalar()` to determine the type of input and then handle it accordingly. By validating input data before using it in the code, developers can prevent errors and ensure the code behaves as expected.

$input = $_POST['data'];

if (is_array($input)) {
    // Handle array input
    foreach ($input as $item) {
        // Process each item in the array
    }
} elseif (is_scalar($input)) {
    // Handle single value input
    // Process the single value
} else {
    // Handle invalid input
    echo "Invalid input type";
}