diff --git a/src/common/Canvas.ts b/src/common/Canvas.ts
index e2e731058..5f41b70dd 100644
--- a/src/common/Canvas.ts
+++ b/src/common/Canvas.ts
@@ -67,8 +67,8 @@ export default class Canvas {
       if (result) {
         this._resizeObserver = new ResizeObserver((entries: ResizeObserverEntry[]) => {
           const entry = entries.find((entry: ResizeObserverEntry) => entry.target === this._element)
-          if (isValid(entry?.devicePixelContentBoxSize?.[0])) {
-            const size = (entry!.devicePixelContentBoxSize[0])!
+          const size = entry?.devicePixelContentBoxSize?.[0]
+          if (isValid(size)) {
             const width = size.inlineSize
             const height = size.blockSize
             if (this._pixelWidth !== width || this._pixelHeight !== height) {