Fix ValueList Peek

RELEASE-NOTES.md

@@ -45,6 +45,7 @@ END TEMPLATE-->
 ### Bugfixes
 
 * Fix ValueList TryPop not clearing element references.
+* Fix ValueList Peek always throwing by referencing the wrong index.
 
 ### Other
 

Robust.Shared.Tests/Collections/ValueListTest.cs

@@ -9,6 +9,27 @@ namespace Robust.Shared.Tests.Collections;
 [TestFixture, TestOf(typeof(ValueList<>))]
 internal sealed class ValueListTest
 {
+    [Test]
+    public void PeekCorrectReference()
+    {
+        var list = new ValueList<bool>(2)
+        {
+            false,
+            true,
+        };
+
+        Assert.That(list.TryPeek(out var popped), Is.True);
+        Assert.That(popped, Is.True);
+
+        list.TryPop(out _);
+
+        Assert.That(list.TryPeek(out popped), Is.True);
+        Assert.That(popped, Is.False);
+
+        list.TryPop(out _);
+        Assert.That(list.TryPeek(out popped), Is.False);
+    }
+
     [Test]
     public void TryPopClearsRemovedReference()
     {

Robust.Shared/Collections/ValueList.cs

@@ -736,7 +736,7 @@ public bool TryPeek([MaybeNullWhen(false)] out T value)
             return false;
         }
 
-        value = _items![Count];
+        value = _items![Count - 1];
         return true;
     }
 }