Add existing to tracked

node_modules/@cesium/engine/Source/Scene/ResourceLoaderState.js

@@ -0,0 +1,62 @@
+// @ts-check
+
+/**
+ * The {@link ResourceLoader} state.
+ *
+ * @enum {number}
+ * @private
+ */
+const ResourceLoaderState = {
+  /**
+   * The resource has not yet been loaded.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  UNLOADED: 0,
+  /**
+   * The resource is loading. In this state, external resources are fetched as needed.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  LOADING: 1,
+  /**
+   * The resource has finished loading, but requires further processing.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  LOADED: 2,
+  /**
+   * The resource is processing. GPU resources are allocated in this state as needed.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  PROCESSING: 3,
+  /**
+   * The resource has finished loading and processing; the results are ready to be used.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  READY: 4,
+  /**
+   * The resource loading or processing has failed due to an error.
+   *
+   * @type {number}
+   * @constant
+   * @private
+   */
+  FAILED: 5,
+};
+
+Object.freeze(ResourceLoaderState);
+
+export default ResourceLoaderState;