3214 Fix crash when students unselects a supervisor idea and presses the back button in the browser

core/src/main/java/se/su/dsv/scipro/match/IdeaServiceImpl.java

@@ -554,6 +554,12 @@ public class IdeaServiceImpl extends AbstractServiceImpl<Idea, Long> implements
 
     @Override
     public boolean canEdit(final Idea idea, final User student) {
+        boolean isAuthor = idea.getIdeaParticipations()
+                .stream()
+                .anyMatch(ip -> Objects.equals(student, ip.getUser()));
+        if (!isAuthor) {
+            return false;
+        }
         final ApplicationPeriod applicationPeriod = idea.getApplicationPeriod();
         return applicationPeriodService.isOpen(applicationPeriod)
                 || (idea.getType() == Type.STUDENT && applicationPeriodService.hasCurrentSubmitIdeaExemption(applicationPeriod, student))

view/src/main/java/se/su/dsv/scipro/match/ProjectIdeaDetailsPage.java

@@ -33,7 +33,7 @@ public class ProjectIdeaDetailsPage extends AbstractIdeaProjectPage implements M
                 .stream()
                 .anyMatch(ideaParticipation -> ideaParticipation.getUser().equals(loggedInUser()));
         if (!isAuthor) {
-            throw new RestartResponseException(getApplication().getHomePage());
+            throw new RestartResponseException(ProjectIdeaStartPage.class);
         }
 
         final DetachableServiceModel<Idea> ideaModel = new DetachableServiceModel<>(ideaService, idea);