Fix file-list is not reloaded when clicking on change number

When user change patch range from patchset 1 -> patchset 2. File list
correctly shows file change between 1-2. When user clicks on change
number, patchset range is reset to base vs patchset 2. However
file list is not reloaded to show changes base vs 2.

This is caused because patchNum is undefined, which is first check
in file-list reload function. It works ok on first render, because
patch gr-patch-range-select set latest to patchNum.

Google-Bug-Id: b/230097909
Release-Notes: skip
Change-Id: Icb96b5d7d861adfb4c8a4d0e4b1209b4975ada13
diff --git a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
index e6d89a1..7e4cf2c 100644
--- a/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
+++ b/polygerrit-ui/app/elements/change/gr-change-view/gr-change-view.ts
@@ -1284,6 +1284,10 @@
     if (value.basePatchNum === undefined)
       value.basePatchNum = ParentPatchSetNum;
 
+    if (value.patchNum === undefined) {
+      value.patchNum = computeLatestPatchNum(this._allPatchSets);
+    }
+
     const patchChanged = this.hasPatchRangeChanged(value);
     let patchNumChanged = this.hasPatchNumChanged(value);