What best practices should be followed when addressing undefined variable notices in PHP scripts during a migration process?

When addressing undefined variable notices in PHP scripts during a migration process, it is important to initialize variables before using them to avoid errors. One common approach is to use isset() or empty() functions to check if a variable is set before using it in the code.

// Check if the variable is set before using it
if(isset($variable_name)){
    // Use the variable here
    echo $variable_name;
} else {
    // Handle the case where the variable is not set
    echo "Variable is not set";
}