problem with [coder] tags in article

[eluser]narkaT[/eluser]
[quote author="double_d" date="1228165872"]escaping square brackets gives me error when returning data from array ...[/quote]

because no matches are found.
you should check if the expression matched anything before working with the "result":

Code:

if ( preg_match(/*....*/) ) {
    // your code
}

your expression won't match anything containing newlines because
the appropriate pattern modifier is missing