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 testExprValue;
		}
		Object vv1 = null;
		Object vv2 = null;
		if ( v1 != null )
		{
			vv1 = evaluate( v1.getText( ) );
		}
		if ( v2 != null )
		{
			vv2 = evaluate( v2.getText( ) );
		}
		try
		{
			return ScriptEvalUtil.evalConditionalExpr( testExprValue, expr
					.getOperator( ), vv1, vv2 );
		}
		catch ( Exception e )
		{
			log.log( Level.SEVERE, e.getMessage( ), e );
			addException( new EngineException(
					MessageConstants.INVALID_EXPRESSION_ERROR, expr, e ) );
			return Boolean.FALSE;
		}
	}
	/**
	 * execute the script. simply evaluate the script, and drop the return value
	 * 
	 * @param script
	 *            script to be executed