fix rce image insertion when editing html

fixes CORE-1625

test plan:
- edit a wiki page
- switch to html editor
- upload multiple images from the sidebar
- multiple uploads should work

Change-Id: Iad9759ce73b7c2fd1ccd136269d4bd3fc2c99a60
Reviewed-on: https://gerrit.instructure.com/157401
Tested-by: Jenkins
Reviewed-by: Clay Diffrient <cdiffrient@instructure.com>
QA-Review: Jeremy Putnam <jeremyp@instructure.com>
Product-Review: Brent Burgoyne <bburgoyne@instructure.com>

packages/canvas-rce/src/rce/RCEWrapper.js

@@ -99,9 +99,9 @@ export default class RCEWrapper extends React.Component {
   insertImage(image) {
     const editor = this.mceInstance();
     const element = contentInsertion.insertImage(editor, image);
-    if (element.complete) {
+    if (element && element.complete) {
       this.contentInserted(element);
-    } else {
+    } else if (element) {
       element.onload = () => this.contentInserted(element);
       element.onerror = () => this.checkImageLoadError(element);
     }

packages/canvas-rce/test/module/RCEWrapper.test.js

@@ -248,6 +248,14 @@ describe("RCEWrapper", () => {
       contentInsertion.insertLink.restore();
     });
 
+    describe("insert image", () => {
+      it("works when no element is returned from content insertion", () => {
+        sinon.stub(contentInsertion, "insertImage").returns(null);
+        instance.insertImage({});
+        contentInsertion.insertImage.restore();
+      })
+    })
+
     describe("indicator", () => {
       it("does not indicate() if editor is hidden", () => {
         let indicateDefaultStub = sinon.stub(indicateModule, "default");