Fix stats export on 2.6. (#11730)

This was broken by my History revamp changes.
Also fixes formatting on a comment and removes an unnecessary toString() on a param.

game-app/game-core/src/main/java/games/strategy/engine/history/History.java

@@ -56,7 +56,6 @@ public HistoryWriter getHistoryWriter() {
   }
 
   public HistoryNode enableSeeking(final HistoryPanel panel) {
-    Preconditions.checkNotNull(panel);
     Preconditions.checkState(!seekingEnabled);
     this.panel = panel;
     nextChangeIndex = changes.size();

game-app/game-headed/src/main/java/games/strategy/triplea/ui/menubar/ExportMenu.java

@@ -167,8 +167,7 @@ private void createAndSaveStats(final boolean showPhaseStats) {
     if (clone == null) {
       return;
     }
-    try (PrintWriter writer =
-            new PrintWriter(chooser.getSelectedFile(), StandardCharsets.UTF_8.toString());
+    try (PrintWriter writer = new PrintWriter(chooser.getSelectedFile(), StandardCharsets.UTF_8);
         GameData.Unlocker ignored = gameData.acquireReadLock()) {
       writer.append(defaultFileName).println(',');
       writer.append("TripleA Engine Version: ,");
@@ -257,8 +256,7 @@ private void createAndSaveStats(final boolean showPhaseStats) {
       final List<GamePlayer> players = clone.getPlayerList().getSortedPlayers();
 
       // extended stats covers stuff that doesn't show up in the game stats menu bar, like custom
-      // resources or tech
-      // tokens or # techs, etc.
+      // resources or tech  tokens or # techs, etc.
       final Iterable<IStat> stats =
           Iterables.concat(
               List.of(statPanel.getStats()), List.of(statPanel.getStatsExtended(gameData)));
@@ -273,6 +271,7 @@ private void createAndSaveStats(final boolean showPhaseStats) {
         }
       }
       writer.println();
+      clone.getHistory().enableSeeking(null);
       clone.getHistory().gotoNode(clone.getHistory().getLastNode());
       final Enumeration<TreeNode> nodes =
           ((DefaultMutableTreeNode) clone.getHistory().getRoot()).preorderEnumeration();