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
this.dataSource = dataSource;
		}
		catch ( IOException e )
		{
			log.log( Level.SEVERE, "Failed to open the data source", e ); 
		}
	}
	
	public IDocArchiveReader getDataSource()
	{
		return dataSource;
	}
	
	public IResultSet executeQuery( IResultSet parent,
			IBaseQueryDefinition query ) throws BirtException
	{
		IDataEngine dataEngine = getDataEngine( );
		rset = dataEngine.execute( parent, query );
		return rset;
	}
	public IResultSet getResultSet( )
	{
		return rset;
	}
	
	public void setResultSet(IResultSet rset)
	{
		this.rset = rset;
	}
	public boolean hasErrors( )