Shows and error trace of the error message in the console if the console is available.

@param {string} [errorMessage=""] The error message.
@returns {void}
function showTrace( errorMessage ) {
	if ( isUndefined( errorMessage ) ) {
		errorMessage = "";
	}

	if (
		! isUndefined( console ) &&
		! isUndefined( console.trace )
	) {
		console.trace( errorMessage );
	}
}