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/ExtensionLoader.java
{
		static final String PROPERTY_TAG = "property"; 
		static final String CHOICE_TAG = "choice"; 
		static final String PROPERTY_GROUP_TAG = "propertyGroup"; 
		static final String PROPERTY_VISIBILITY_TAG = "propertyVisibility"; 
		static final String EXTENSION_NAME_ATTRIB = "extensionName"; 
		static final String NAME_ATTRIB = "name"; 
		static final String DISPLAY_NAME_ID_ATTRIB = "displayNameID"; 
		static final String TYPE_ATTRIB = "type"; 
		static final String CAN_INHERIT_ATTRIB = "canInherit"; 
		static final String DEFAULT_VALUE_ATTRIB = "defaultValue"; 
		static final String VALUE_ATTRIB = "value"; 
		static final String VISIBILITY_ATTRIB = "visibility"; 
		static final String DEFAULT_DISPLAY_NAME_ATTRIB = "defaultDisplayName"; 
		static final String IS_ENCRYPTABLE_ATTRIB = "isEncryptable"; 
		IExtension extension;
		ExtensionElementLoader( IExtension extension )
		{
			this.extension = extension;
		}
		/**
		 * Loads the extension element definition 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