linking to images problem / suggestion

I notice that if a user uses the bbcode button to link to an image and they do what a lot of users do every day and that is to link to an image somewhere that has a complicated URL, like via a cdn or some photo service like photobucket that makes it difficult to actually hotlink an image, that the url will be some variation that doesn't end in a file extension e.g. "http://testsite.com/image.jpg?large.version";

After the user submits their post/reply the post will show with a language error even if the photo link was only part of the content of their post. The error will display as the text of the completed post/reply and it will be like this:

Warning: preg_replace(): Compilation failed: missing terminating ] for character class at offset 131 in /public_html/administrator/components/com_easydiscuss/includes/string/string.php on line 346

This also happens the same way even if the url is linking to an actual image file like:
"http://testsite.com/image.jpg";
but pehaps they were copying and pasting so they copied and pasted it like:
"tp://http://testsite.com/image.jpg";
or
"http://testsite.com/image.jp";

The way this error is handled needs to be fixed but even aside from that I would like to make a suggestion on how to help reduce this error from occurring. Two options include:

1) some sort of checking to ensure a properly formed URL that occurs before the post is completed.
2) some sort of fixing such as correcting common issues like: removing anything in a url after an image file like automatically removing anything after .jpg, .png or .jpeg