fix: #1075 Returning to the Study List before all series have finishe… (#1090)

* fix: #1075 Returning to the Study List before all series have finished loading throws multiple errors in console

* fix: 🐛 Addressing review feedback from issue #1075

Adding support for cancelable pattern

Closes: #1075

* fix: 🐛 update unit test for exports

Closes: #1075

platform/core/src/utils/index.js

@@ -11,6 +11,7 @@ import writeScript from './writeScript.js';
 import DicomLoaderService from './dicomLoaderService.js';
 import b64toBlob from './b64toBlob.js';
 import * as urlUtil from './urlUtil';
+import makeCancelable from './makeCancelable';
 
 const utils = {
   guid,
@@ -27,6 +28,7 @@ const utils = {
   DICOMTagDescriptions,
   DicomLoaderService,
   urlUtil,
+  makeCancelable,
 };
 
 export {
@@ -44,6 +46,7 @@ export {
   DICOMTagDescriptions,
   DicomLoaderService,
   urlUtil,
+  makeCancelable,
 };
 
 export default utils;

platform/core/src/utils/index.test.js

@@ -17,6 +17,7 @@ describe('Top level exports', () => {
       'DICOMTagDescriptions',
       'DicomLoaderService',
       'urlUtil',
+      'makeCancelable',
     ].sort();
 
     const exports = Object.keys(utils.default).sort();

platform/core/src/utils/makeCancelable.js

@@ -0,0 +1,19 @@
+export default function makeCancelable(thenable) {
+  let isCanceled = false;
+  const promise = Promise.resolve(thenable).then(
+    function(result) {
+      if (isCanceled) throw Object.freeze({ isCanceled });
+      return result;
+    },
+    function(error) {
+      if (isCanceled) throw Object.freeze({ isCanceled, error });
+      throw error;
+    }
+  );
+  return Object.assign(Object.create(promise), {
+    then: promise.then.bind(promise),
+    cancel() {
+      isCanceled = true;
+    },
+  });
+}