fix(studio): don't crash resizing an element whose keyframes were removed

commitWholePropertyOffset reduced the tween's keyframe list to find the
"nearest" stop without an initial value. When a to()/from() tween had been
collapsed to a zero-duration immediateRender hold (what removeAllKeyframes
leaves behind), synthesizeFlatTweenKeyframes correctly treats it as a
static hold and returns null, leaving an empty keyframe list — so the
reduce threw "Reduce of empty array with no initial value". Reachable by
resizing such an element with auto-keyframe recording off.

With no keyframe shape to preserve, persist the flat value directly via an
update-properties mutation instead.

packages/studio/src/hooks/gsapWholePropertyOffsetCommit.test.ts

@@ -133,4 +133,30 @@ describe("commitWholePropertyOffset", () => {
     });
     expect(keyframes[1]).toEqual({ percentage: 100, properties: { x: 120, opacity: 0.5 } });
   });
+
+  it("persists a flat update instead of crashing when the tween has no synthesizable shape", async () => {
+    // Regression: removeAllKeyframesFromScript collapses a keyframed tween into a
+    // zero-duration immediateRender hold — synthesizeFlatTweenKeyframes treats that
+    // as a static hold (returns null), so `kfs` is empty. Resizing this element with
+    // auto-keyframe off used to call `kfs.reduce(...)` with no initial value, which
+    // throws "Reduce of empty array with no initial value".
+    const anim = {
+      id: "#box-hold",
+      targetSelector: "#box",
+      method: "to",
+      resolvedStart: 0,
+      duration: 0,
+      properties: { width: 200 },
+      extras: { immediateRender: "__raw:true" },
+    } as unknown as GsapAnimation;
+
+    const { mutations, callbacks } = recordingCallbacks();
+    await expect(
+      commitWholePropertyOffset(selection(), anim, { width: 300 }, 0, null, callbacks, "Resize"),
+    ).resolves.toBeUndefined();
+
+    expect(mutations).toEqual([
+      { type: "update-properties", animationId: "#box-hold", properties: { width: 300 } },
+    ]);
+  });
 });

packages/studio/src/hooks/gsapWholePropertyOffsetCommit.ts

@@ -43,9 +43,18 @@ export async function commitWholePropertyOffset(
     typeof props[key] === "number" ? (props[key] as number) : (PROPERTY_DEFAULTS[key] ?? 0);
 
   const kfs =
-    effectiveAnim.keyframes?.keyframes ??
-    synthesizeFlatTweenKeyframes(effectiveAnim)?.keyframes ??
-    [];
+    effectiveAnim.keyframes?.keyframes ?? synthesizeFlatTweenKeyframes(effectiveAnim)?.keyframes;
+  if (!kfs || kfs.length === 0) {
+    // A `to()`/`from()` collapsed to a zero-duration immediateRender hold (what
+    // removeAllKeyframesFromScript leaves behind) has no shape to preserve —
+    // just persist the flat value instead of replacing with an empty keyframe list.
+    await callbacks.commitMutation(
+      selection,
+      { type: "update-properties", animationId: effectiveAnim.id, properties: newValues },
+      { label, softReload: true },
+    );
+    return;
+  }
   const nearest = kfs.reduce((best, kf) =>
     Math.abs(kf.percentage - currentPct) < Math.abs(best.percentage - currentPct) ? kf : best,
   );