Bug 165278 this.getDisplayContent()="" in script of text will destroy preview[0801]
Description: this.getDisplayContent()="" in script of text will destroy preview Build number:2.1.2.v20061120 and 2.2.0.v20061117 Steps to reproduce: 1. Insert a text item, select it and switch to script editor 2. Input this.getDisplayContent()="" and preview Expected result: Error message about the incorrect script. Actual result: In 2.1.2, I saw HTTP Status 500 - type Exception report message description The server encountered an internal error () that prevented it from fulfilling this request. In 2.2.0, I saw error dialog with java.lang.ClassCastException.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutionContext.java
private IReportContent reportContent;
	/**
	 * the current executed design.
	 */
	private ReportItemDesign design;
	/**
	 * The current content element to be executed or loaded
	 */
	private IContent content;
	
	/**
	 * the current opened result set 
	 */
	private IResultSet rset; 
	/**
	 * A stack of handle objects, with the current one on the top
	 */
	private Stack reportHandles = new Stack( );
	/**
	 * total page
	 */
	private long totalPage;
	/**
	 * current page number
	 */
	private long pageNumber;
	/**
	 * A list of script errors found in onPrepare. These will be added to the
	 * IReportContent, when one is available
	 *