wp-theme-mod-sane-defaults.php

<?php
/**
 * Collects all the default theme mods value in an array
 * @return array All the default theme mods values
 */
function prefix_get_theme_mods_defaults() {
    $defaults = array(
    	// Site footer options
		'option1' => 'value1', 
		'option2' => 'value2', 
	);
	return apply_filters( 'prefix_get_theme_mods_defaults', $defaults );
}

/**
 * Making sane defaults for the theme mods to return
 * @return mixed Return array of theme mods or other data type if theme mod id is passed
 */
function prefix_get_theme_mods( $theme_mod_id='' ) {
	// Theme Mods API:
	$merged_theme_mods = wp_parse_args( 
	        get_theme_mods(), 
	        prefix_get_theme_mods_defaults() 
	    );
	
    if ( $theme_mod_id )
    	return $merged_theme_mods[ $theme_mod_id ];
    else
	    return $merged_theme_mods;
}