Fix linter errors

Bug: b/262243662
Test: npm run tslint:check
Change-Id: I783d93e00421dc532831cce1566c16df6b9e112a

tools/winscope/src/trace/flickerlib/layers/Layer.ts

diff --git a/tools/winscope/src/trace/flickerlib/layers/Layer.ts b/tools/winscope/src/trace/flickerlib/layers/Layer.ts
index ac25b27..077d1b8 100644
--- a/tools/winscope/src/trace/flickerlib/layers/Layer.ts
+++ b/tools/winscope/src/trace/flickerlib/layers/Layer.ts
@@ -49,7 +49,7 @@
   const inputRegion = toRegion(
     proto.inputWindowInfo ? proto.inputWindowInfo.touchableRegion : null
   );
-  let crop: Rect = toCropRect(proto.crop);
+  const crop: Rect = toCropRect(proto.crop);
 
   const properties = new LayerProperties(
     visibleRegion,