Well, downloaded opera 9 and found that errors, even JS ones, are only shown in the error console. What I got was:
JavaScript - http://themofoclan.com/component/option,com_smf/Itemid,51/action,post/topic,7294.15/num_replies,20/
Unknown thread
Error:
name: TypeError
message: Statement on line 74: Could not convert undefined or null to object
Backtrace:
Line 74 of inline#3 script in http://themofoclan.com/component/option,com_smf/Itemid,51/action,post/topic,7294.15/num_replies,20/
var i, preview = ((XMLDoc.getElementsByTagName("smf"))[0].getElementsByTagName("preview"))[0];
Line 60 of linked script http://themofoclan.com/forums/Themes/default/script.js?jrc1
callback(sendDoc.responseXML);
At unknown location
[statement source code not available]