fix: don't throw undefined error if rapidly zooming browser in some e…

…nvironments

Some users were reporting the following error when zooming their browser
(not Puck's internal zoom) quickly:

> TypeError: Cannot read properties of undefined (reading 'value') at
ViewportControls

Unable to reproduce, but user confirmed this helped.

packages/core/components/ViewportControls/index.tsx

@@ -122,7 +122,7 @@ export const ViewportControls = ({
       <div className={getClassName("divider")} />
       <IconButton
         title="Zoom viewport out"
-        disabled={zoom <= zoomOptions[0].value}
+        disabled={zoom <= zoomOptions[0]?.value}
         onClick={(e) => {
           e.stopPropagation();
           onZoom(
@@ -139,7 +139,7 @@ export const ViewportControls = ({
       </IconButton>
       <IconButton
         title="Zoom viewport in"
-        disabled={zoom >= zoomOptions[zoomOptions.length - 1].value}
+        disabled={zoom >= zoomOptions[zoomOptions.length - 1]?.value}
         onClick={(e) => {
           e.stopPropagation();