The fix for
TAP5-1147 causes an exception when it finds an element with a function for an attribute value under IE 8. In the purge function in tapestry.js starting at line 640, the count of attributes is kept in a variable, then the attributes are processed starting at the beginning. When an attribute is found where the value is a function, the attribute is removed and the count of attributes changes. When the loop gets to the end, an exception is thrown because attrs[i] is undefined.