Fix lock issue with workspace dialog

CURA-4405

- Add try-except around lock release
- Fix closing the dialog with ESC

plugins/3MFReader/WorkspaceDialog.qml

@@ -10,6 +10,7 @@ import UM 1.1 as UM
 
 UM.Dialog
 {
+    id: base
     title: catalog.i18nc("@title:window", "Open Project")
 
     minimumWidth: 500 * screenScaleFactor
@@ -30,6 +31,7 @@ UM.Dialog
             materialResolveComboBox.currentIndex = 0
         }
     }
+
     Item
     {
         anchors.fill: parent
@@ -377,7 +379,7 @@ UM.Dialog
             anchors.right: ok_button.left
             anchors.rightMargin: 2 * screenScaleFactor
         }
-         Button
+        Button
         {
             id: ok_button
             text: catalog.i18nc("@action:button","Open");
@@ -386,4 +388,10 @@ UM.Dialog
             anchors.right: parent.right
         }
     }
+
+    function reject() {
+        manager.onCancelButtonClicked();
+        base.visible = false;
+        base.rejected();
+    }
 }