When the author has been deleted the export of data no longer works :
Caused by: java.lang.NullPointerException: Cannot invoke "org.ametys.core.user.User.getFullName()" because the return value of "org.ametys.core.user.UserManager.getUser(org.ametys.core.user.UserIdentity)" is null at org.ametys.plugins.forms.generators.FormEntryInformationGenerator#_saxEntry:131 at org.ametys.plugins.forms.generators.FormEntriesGenerator#generate:85 at org.apache.cocoon.components.pipeline.AbstractProcessingPipeline#processXMLPipeline:581 ... 76 more