smartlist: don't display misleading 'last interaction' date

If a conversation has no interactions (which shouldn't happen normally,
but sometimes occurs in practice), then its LastInteractionTimeStamp
will be zero, which causes the last interaction date in the smartlist to
be wrongly displayed as 31/12/1969 or 1/1/1970. This patch adds a check
to prevent this.

GitLab: #1794
Change-Id: I1384d6675c9fcaa1904bb6e1706589305b7618e9

src/app/mainview/components/SmartListItemDelegate.qml

@@ -38,9 +38,9 @@ ItemDelegate {
 
     highlighted: ListView.isCurrentItem
     property bool interactive: true
-    property string lastInteractionDate: LastInteractionTimeStamp === undefined ? "" : LastInteractionTimeStamp
 
-    property string lastInteractionFormattedDate: MessagesAdapter.getBestFormattedDate(lastInteractionDate)
+    property int lastInteractionTimeStamp: LastInteractionTimeStamp
+    property string lastInteractionFormattedDate: MessagesAdapter.getBestFormattedDate(lastInteractionTimeStamp)
 
     property bool showSharePositionIndicator: PositionManager.isPositionSharedToConv(accountId, UID)
     property bool showSharedPositionIndicator: PositionManager.isConvSharingPosition(accountId, UID)
@@ -58,7 +58,7 @@ ItemDelegate {
     Connections {
         target: MessagesAdapter
         function onTimestampUpdated() {
-            lastInteractionFormattedDate = MessagesAdapter.getBestFormattedDate(lastInteractionDate);
+            lastInteractionFormattedDate = MessagesAdapter.getBestFormattedDate(lastInteractionTimeStamp);
         }
     }
 
@@ -130,7 +130,7 @@ ItemDelegate {
                 color: JamiTheme.textColor
             }
             RowLayout {
-                visible: ContactType !== Profile.Type.TEMPORARY && !IsBanned && lastInteractionFormattedDate !== undefined && interactive
+                visible: ContactType !== Profile.Type.TEMPORARY && !IsBanned && lastInteractionTimeStamp > 0 && interactive
                 Layout.fillWidth: true
                 Layout.minimumHeight: 20
                 Layout.alignment: Qt.AlignTop
@@ -138,7 +138,7 @@ ItemDelegate {
                 // last Interaction date
                 Text {
                     Layout.alignment: Qt.AlignVCenter
-                    text: lastInteractionFormattedDate === undefined ? "" : lastInteractionFormattedDate
+                    text: lastInteractionFormattedDate
                     textFormat: TextEdit.PlainText
                     font.pointSize: JamiTheme.smallFontSize
                     font.weight: UnreadMessagesCount ? Font.DemiBold : Font.Normal