What are some common error messages that may appear when attempting to modify a sorting function in PHP?

When attempting to modify a sorting function in PHP, common error messages may include "Undefined variable" if the variable being used is not declared or initialized properly, "Invalid argument supplied for foreach()" if the function expects an array but receives a different data type, or "Unexpected T_VARIABLE" if there is a syntax error in the code. To solve these issues, make sure to properly declare and initialize variables, ensure that the function is receiving the correct data type, and check for any syntax errors in the code.

// Example of fixing "Undefined variable" error
$numbers = [3, 1, 2, 5, 4];
sort($numbers);
print_r($numbers);