Fix interpolator being lost when moving keyframe to the end (fixes #62)

src/integration-test/java/com/replaymod/core/ReplayModIntegrationTest.java

@@ -1,6 +1,7 @@
 package com.replaymod.core;
 
 import com.replaymod.core.regression.RegressionTest60;
+import com.replaymod.core.regression.RegressionTest62;
 import com.replaymod.extra.DownloadOpenEye;
 import com.replaymod.online.SkipLogin;
 import com.replaymod.recording.CreateSPWorld;
@@ -44,6 +45,7 @@ public class ReplayModIntegrationTest {
                 new LoadReplay(),
 
                 new RegressionTest60(),
+                new RegressionTest62(),
 
                 // new AbstractTask() {}, // Uncomment to not exit on success (useful for writing more tests)
                 new ExitReplay()

src/integration-test/java/com/replaymod/core/regression/RegressionTest62.java

@@ -0,0 +1,28 @@
+package com.replaymod.core.regression;
+
+import com.replaymod.core.CompositeTask;
+import com.replaymod.core.Task;
+import com.replaymod.replay.overlay.OverlayGui;
+import com.replaymod.simplepathing.GuiPathingTasks;
+
+/**
+ * Regression test: #62 Swapping the only two existing keyframes causes NPE
+ */
+public class RegressionTest62 extends CompositeTask {
+    public RegressionTest62() {
+        super(new Task[]{
+                OverlayGui.whileOpened(
+                        // Place first keyframe
+                        Task.click(130, 50),
+                        new GuiPathingTasks.ClickPositionKeyframeButton(),
+                        // Place second keyframe
+                        Task.click(150, 50),
+                        new GuiPathingTasks.ClickPositionKeyframeButton(),
+                        // Move first keyframe past second keyframe
+                        Task.click(130,50),
+                        Task.drag(170,50)
+                ),
+                new GuiPathingTasks.ClearKeyframeTimeline()
+        });
+    }
+}