@uppy/dashboard: fix handling of null for doneButtonHandler

[aduh95]

As documented, null should not be treated the same as undefined.

Fixes: #5282

[github-actions]

Diff output files

diff --git a/packages/@uppy/dashboard/lib/Dashboard.js b/packages/@uppy/dashboard/lib/Dashboard.js
index 05cad99..31f37a0 100644
--- a/packages/@uppy/dashboard/lib/Dashboard.js
+++ b/packages/@uppy/dashboard/lib/Dashboard.js
@@ -74,7 +74,7 @@ const defaultOptions = {
   autoOpenFileEditor: false,
   disabled: false,
   disableLocalFiles: false,
-  doneButtonHandler: null,
+  doneButtonHandler: undefined,
   onRequestCloseModal: null,
 };
 var _disabledNodes = _classPrivateFieldLooseKey("disabledNodes");
@@ -90,7 +90,7 @@ var _autoDiscoverPlugins = _classPrivateFieldLooseKey("autoDiscoverPlugins");
 var _addSupportedPluginIfNoTarget = _classPrivateFieldLooseKey("addSupportedPluginIfNoTarget");
 export default class Dashboard extends UIPlugin {
   constructor(uppy, _opts) {
-    var _this$opts4, _this$opts4$doneButto, _this$opts5, _this$opts5$onRequest;
+    var _this$opts4, _this$opts4$onRequest;
     let autoOpen;
     if (!_opts) {
       autoOpen = null;
@@ -1071,15 +1071,15 @@ export default class Dashboard extends UIPlugin {
     this.title = "Dashboard";
     this.type = "orchestrator";
     this.defaultLocale = locale;
-    (_this$opts4$doneButto = (_this$opts4 = this.opts).doneButtonHandler) != null
-      ? _this$opts4$doneButto
-      : _this$opts4.doneButtonHandler = () => {
+    if (this.opts.doneButtonHandler === undefined) {
+      this.opts.doneButtonHandler = () => {
         this.uppy.clearUploadedFiles();
         this.requestCloseModal();
       };
-    (_this$opts5$onRequest = (_this$opts5 = this.opts).onRequestCloseModal) != null
-      ? _this$opts5$onRequest
-      : _this$opts5.onRequestCloseModal = () => this.closeModal();
+    }
+    (_this$opts4$onRequest = (_this$opts4 = this.opts).onRequestCloseModal) != null
+      ? _this$opts4$onRequest
+      : _this$opts4.onRequestCloseModal = () => this.closeModal();
     this.i18nInit();
   }
 }