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
{
		return !elementExceptions.isEmpty( );
	}
	/**
	 * Returns list or errors, the max count of the errors is
	 * <code>MAX_ERRORS</code>
	 * 
	 * @return error list which has max error size limited to
	 *         <code>MAX_ERRORS</code>
	 */
	public List getErrors( )
	{
		List errors = this.getAllErrors( );
		if ( errors.size( ) > MAX_ERRORS )
		{
			errors = errors.subList( 0, MAX_ERRORS - 1 );
		}
		return errors;
	}
	
	/**
	 * Returns all errors.
	 * 
	 * @return list of all the errors.
	 */
	public List getAllErrors( )
	{
		List errors = new ArrayList( );
		Iterator entries = elementExceptions.entrySet( ).iterator( );
		while( entries.hasNext( ) )