Bug 124629 Use Top/Bottom n in a field containing null value inside will cause DataException.
Description: Use Top/Bottom n in a field containing null value inside will cause DataException. Steps to reproduce: 1. New a data source and dataset 2. Add a filter on a field, set operator to top 5 3. Click Preview Result. Result: A BIRT exception occurred. Plug-in Provider:Eclipse.org Plug-in Name:BIRT Data Engine Plug-in ID:org.eclipse.birt.data Version:2.0.0 Error Code:data.engine.DataConversionError Error Message:An error happened in data type conversion. Can not convert the value of {NULL_VALUE_!@#$%^&} to Double type.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/script/NEvaluator.java
}
				}
				catch ( BirtException e )
				{
					throw DataException.wrap(e);
				}
			}
		}
	}
	
	/**
	 * Do the second pass
	 * @param N
	 * @return
	 */
	private boolean doSecondPass( )
	{
		secondPassRowNumberCounter++;
		if( secondPassRowNumberCounter > this.filterPassController.getSecondPassRowCount() )
			this.filterPassController.setSecondPassRowCount( secondPassRowNumberCounter );
		else
			this.secondPassRowNumberCounter = this.filterPassController.getSecondPassRowCount();
		
		if ( qualifiedRowCounter < N )
		{
			for ( int i = 0; i < N; i++ )
			{
				if ( rowIdList[i] == secondPassRowNumberCounter )
				{
					qualifiedRowCounter++;