Lectures: rs in new absence wizard if back and forth from the contact form

Error#: I1091-J451 Identity: Category/Class: org.olat.core.gui.exception.ExceptionWindowController 
Referer: https://testing.frentix.com/test8/auth/CoachSite/0/Lectures/0/Absences/0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/77.0.3865.120 Safari/537.36
Exception: ExceptionWindowController: Throwable occurred, logging the full stacktrace: java.lang.NullPointerException 
 at org.olat.core.gui.components.form.flexible.impl.elements.richText.RichTextElementImpl.getValue(RichTextElementImpl.java:117)
 at org.olat.modules.lecture.ui.coach.ContactTeachersController.validateFormLogic(ContactTeachersController.java:166)
 at org.olat.core.gui.components.form.flexible.impl.Form.validate(Form.java:460)
 at org.olat.core.gui.components.form.flexible.impl.Form.submit(Form.java:440)
 at org.olat.core.gui.components.form.flexible.impl.Form.submitAndNext(Form.java:432)
 at org.olat.core.gui.control.generic.wizard.StepsMainRunController.formInnerEvent(StepsMainRunController.java:207)
 at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:430)
 at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:206)
 at org.olat.core.gui.components.AbstractComponent$1.run(AbstractComponent.java:240)
 at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)
 at org.olat.core.gui.components.AbstractComponent.fireEvent(AbstractComponent.java:238)
 at org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer.fireFormEvent(FormWrapperContainer.java:131)
 at org.olat.core.gui.components.form.flexible.impl.Form.fireFormEvent(Form.java:717)
 at org.olat.core.gui.components.form.flexible.impl.elements.FormLinkImpl.dispatchFormRequest(FormLinkImpl.java:239)
 at org.olat.core.gui.components.form.flexible.impl.FormItemImpl.doDispatchFormRequest(FormItemImpl.java:561)
 at org.olat.core.gui.components.form.flexible.impl.Form.evalFormRequest(Form.java:296)
 at org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer.doDispatchRequest(FormWrapperContainer.java:100)
 at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
 at org.olat.core.gui.components.Window.doDispatchToComponent(Window.java:1208)
 at org.olat.core.gui.components.Window.dispatchRequest(Window.java:400)
 at org.olat.core.gui.components.Window.doDispatchRequest(Window.java:284)
 at org.olat.core.gui.components.AbstractComponent.dispatchRequest(AbstractComponent.java:193)
 at org.olat.dispatcher.AuthenticatedDispatcher.processValidDispatchURI(AuthenticatedDispatcher.java:263)
 ...