Index: src/presentation/artifacteditormodel.cpp
===================================================================
--- src/presentation/artifacteditormodel.cpp
+++ src/presentation/artifacteditormodel.cpp
@@ -68,7 +68,7 @@
 
     int rowCount(const QModelIndex &parent) const override
     {
-        if (parent.isValid())
+        if (parent.isValid() || !m_task)
             return 0;
 
         return m_task->attachments().size();
Index: tests/units/presentation/artifacteditormodeltest.cpp
===================================================================
--- tests/units/presentation/artifacteditormodeltest.cpp
+++ tests/units/presentation/artifacteditormodeltest.cpp
@@ -82,6 +82,8 @@
         QVERIFY(model.delegateText().isNull());
         QVERIFY(!model.hasSaveFunction());
         QVERIFY(!model.hasDelegateFunction());
+        auto am = model.attachmentModel();
+        QCOMPARE(am->rowCount(), 0);
     }
 
     void shouldHaveTaskProperties()