Non-existing text-block causes "Fatal error: Maximum function nesting level"

Hi,

Found a bug in your plugin. If one uses text-block with non-existing id/slug then the plugin fails on that with following error message:
“Fatal error: Maximum function nesting level of ‘100’ reached, aborting!“

Affected plugin version: 1.4.2
WP version: 3.6.1

Steps to reproduce:
a) have WordPress installed with plenty of pages (over 200 in my case);
b) install and enable plugin;
c) add random ID for text-block on page, e.g. [text-blocks id=nonexistingslug]
d) save page and see resulting page (or error log)

I traced the problem down to function “show_text_block” in text-blocks.php (starting from line 235).
It expects $id to be numeric (line 238), if not then tries to get ID from path/slug with “get_page_by_path” (line 240). That function doesn’t guarantee to produce meaningful result.

I fixed this with this patch after is_numeric check: added new lines from 244 to 247:

if (!$id)
{
	return '';
}

Please add this fix (or other resolution) in next release.

http://wordpress.org/plugins/reusable-text-blocks/