Bug 163018 An error extension will lead the report contain chart can't be opened and can not new a report.
Details: An error extension will lead the report contain chart can't open In org.eclipse.birt.report.tests.model has an error extension. When run the birt use workbenck, the report contain chart can't be opened and it can not new a report.
model/org.eclipse.birt.report.model/src/org/eclipse/birt/report/model/metadata/PeerExtensionLoader.java
private static final String SUB_TYPE_ATTRIB = "subType"; 
		private static final String IS_LIST_ATTRIB = "isList"; 
		/**
		 * List of the property types that are allowed for the extensions.
		 */
		List allowedPropertyTypes = null;
		/**
		 * List of the property types that are allowed for sub-type for the
		 * extensions.
		 */
		List allowedSubPropertyTypes = null;
		PeerExtensionElementLoader( IExtension extension )
		{
			super( extension );
		}
		/**
		 * Loads the extended element and its properties.
		 * 
		 * @param elementTag
		 *            the element tag
		 * @throws MetaDataException
		 *             if error encountered when adding the element to metadata
		 *             dictionary.
		 * @throws ExtensionException
		 *             if the class some attribute specifies can not be
		 *             instanced.
		 */
		void loadElement( IConfigurationElement elementTag )
				throws MetaDataException, ExtensionException
		{