upgrade cesium

package.json

     "@babel/plugin-proposal-class-properties": "^7.18.6",
     "@babel/plugin-transform-runtime": "^7.21.4",
     "@babel/preset-env": "^7.21.5",
-    "@cesium/engine": "^2.3.0",
+    "@cesium/engine": "^2.4.1",
     "@rollup/plugin-babel": "^6.0.3",
     "@rollup/plugin-commonjs": "^24.1.0",
     "@rollup/plugin-node-resolve": "^15.0.2",

src/modules/exts/Viewer.js

 
       if (defined(zoomTarget.imageryProvider)) {
         // This is here for backward compatibility. It can be removed when readyPromise is removed.
-        rectanglePromise = zoomTarget.imageryProvider._readyPromise.then(() => {
+        let promise = Promise.resolve()
+        if (defined(zoomTarget.imageryProvider._readyPromise)) {
+          promise = zoomTarget.imageryProvider._readyPromise
+        } else if (defined(zoomTarget.imageryProvider.readyPromise)) {
+          promise = zoomTarget.imageryProvider.readyPromise
+        }
+        rectanglePromise = promise.then(() => {
           return zoomTarget.getImageryRectangle()
         })
       } else {