Bug 136553 [regression]Preview error when set invalid group interval.
Description: Preview error when set invalid group interval. Steps to reproduce: 1. Insert a table 2. Add a group on number column, set interval to Year,1 3. Preview 4. Edit group on string column set interval to Prefix,1 5. Preview Expected result: Error msg about invalid group interval. Actual result: Error happened while running the report
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/DataGenerationEngine.java
logger.log( Level.SEVERE, be.getMessage( ) );
				context.addException( be );
			}
		}
	}
	protected IResultSet doExecuteQuery( IBaseQueryDefinition query )
	{
		assert query instanceof IQueryDefinition;
		IPreparedQuery pQuery = (IPreparedQuery) queryMap.get( query );
		if ( pQuery == null )
		{
			return null;
		}
		try
		{
			String queryID = (String) queryIDMap.get( query );
			Scriptable scope = context.getSharedScope( );
			DteResultSet resultSet = (DteResultSet) getResultSet( );
			String pRsetId = null; 
			long rowId = -1; 
			IQueryResults dteResults; 
			if ( resultSet == null )
			{
				
				dteResults = pQuery.execute( scope );
			}
			else
			{
				pRsetId = resultSet.getQueryResults( ).getID( );
				rowId = resultSet.getCurrentPosition( );