Unexpected runtime error

The runtime has encountered an unexpected error.

Error source

Page Name:/documento.xsp

Exception

Error while executing JavaScript computed expression
Script interpreter error, line=42, col=52: Error calling method 'getPageTitle()' on java class 'com.ibm.xsp.component.UIViewRootEx2'
Error while executing JavaScript computed expression
Script interpreter error, line=1, col=22: 'getCurrentDocument()' is null

JavaScript code

   1: getCurrentDocument().getItemValueString("doc_titolo")

Stack Trace