There can be cases where the composition nodetype goes missing. It should be possible to regenerate the nodetypes file without needing an installation/upgrade.

Reproduce

• Install Magnolia
• Shut down
• Delete the custom_nodetypes.xml file (/magnolia-dx-core-demo-6.2.39/apache-tomcat-9.0.80/webapps/magnoliaAuthor/repositories/magnolia/repository/nodetypes/custom_nodetypes.xml)
• Start up

Expected
The mgnl:composition nodetype should be available.

Actual
The nodetype is missing which can lead to:

NoSuchNodeTypeException: {http://www.magnolia.info/jcr/mgnl}composition

Workaround
Regsiter the nodetypes manually running this Groovy script:

import info.magnolia.objectfactory.Components;
import info.magnolia.repository.Provider;
import info.magnolia.repository.RepositoryManager;

RepositoryManager repositoryManager = Components.getComponent(RepositoryManager.class);
Provider repositoryProvider = repositoryManager.getRepositoryProvider("magnolia");
repositoryProvider.registerNodeTypes("/mgnl-nodetypes/content-editor-nodetypes.cnd"); 

Notes
The problems stems from the fact the nodetype is only registered through code now. We need the nodetype registered through a file configuration as well.