Unexpected runtime error

The runtime has encountered an unexpected error.

Error source

Page Name:/blogpost.xsp
Control Id: _id130

Exception

com.ibm.xsp.exception.EvaluationExceptionEx: Error while executing JavaScript action expression
Error while executing JavaScript action expression
Script interpreter error, line=3, col=31: 'document1.getValue()' is null

JavaScript code

   1: comment.replaceItemValue("$PublicAccess", "1");
   2: currentDocument.setValue("pagename", view.getPageName());
   3: if(document1.getValue("Form").equals("content")){
   4: 	comment.replaceItemValue("commentParent", document1.getValue("contentKey"));
   5: } else {
   6: 	comment.replaceItemValue("commentParent", document1.getValue("postId"));
   7: }

Stack Trace