Bug 210617 NPE occurrs when using report item which is involved with subquery
Build ID: I20071101-2000 Steps To Reproduce: 1. New a datasource and dataset 2. New a table named table1 and binding the dataset. 3. Add a chart in table and set the x and y series. 4. Add some item in layout and binding the result set as table1. Actual reuslt: Preview this report will cause an NPE Since report item sharing is not used in a report item involved with subquery, dte will throw out DataException will a message in CacheResultIterator.getSecondaryIterator(String, Scriptable) to indicate the user this kind of behavior is not valid. In the invoker method like AbstractDataEngine.doExecuteSubQuery(QueryResultSet, ISubqueryDefinition), however, DataException will be caught and then return null to the upper layer, which will raise an NullPointerException. So engine should change the way handling the DataException to display the indicating message properly.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/executor/ExecutorManager.java
{
	/**
	 * item executor type
	 */
	public static final int GRIDITEM = 0;
	public static final int IMAGEITEM = 1;
	public static final int LABELITEM = 2;
	public static final int LISTITEM = 3;
	public static final int TABLEITEM = 4;
	public static final int DYNAMICTEXTITEM = 5;
	public static final int TEXTITEM = 6;
	public static final int DATAITEM = 7;
	public static final int EXTENDEDITEM = 8;
	public static final int TEMPLATEITEM = 9;
	public static final int AUTOTEXTITEM = 10;
	public static final int LISTBANDITEM = 11;
	public static final int TABLEBANDITEM = 12;
	public static final int ROWITEM = 13;
	public static final int CELLITEM = 14;
	public static final int LISTGROUPITEM = 15;
	public static final int TABLEGROUPITEM = 16;