Remove nested Promise from admin email select

ee/app/assets/javascripts/pages/admin/emails/show/admin_email_select.js

-/* eslint-disable no-var, func-names, one-var, no-else-return */
-
 import $ from 'jquery';
 import Api from '~/api';
 import { sprintf, __ } from '~/locale';
 
-function AdminEmailSelect() {
-  import(/* webpackChunkName: 'select2' */ 'select2/select2')
-    .then(() => {
-      $('.ajax-admin-email-select').each(
-        (function(_this) {
-          return function(i, select) {
-            return $(select).select2({
-              placeholder: __('Select group or project'),
-              multiple: $(select).hasClass('multiselect'),
-              minimumInputLength: 0,
-              query(query) {
-                const groupsFetch = Api.groups(query.term, {});
-                const projectsFetch = Api.projects(query.term, {
-                  order_by: 'id',
-                  membership: false,
-                });
-                return Promise.all([projectsFetch, groupsFetch]).then(([projects, groups]) => {
-                  var all, data;
-                  all = {
-                    id: 'all',
-                  };
-                  data = [all].concat(groups, projects);
-                  return query.callback({
-                    results: data,
-                  });
-                });
-              },
-              id(object) {
-                if (object.path_with_namespace) {
-                  return `project-${object.id}`;
-                } else if (object.path) {
-                  return `group-${object.id}`;
-                } else {
-                  return 'all';
-                }
-              },
-              formatResult(...args) {
-                return _this.formatResult(...args);
-              },
-              formatSelection(...args) {
-                return _this.formatSelection(...args);
-              },
-              dropdownCssClass: 'ajax-admin-email-dropdown',
-              escapeMarkup(m) {
-                return m;
-              },
-            });
-          };
-        })(this),
-      );
-    })
-    .catch(() => {});
-}
-
-AdminEmailSelect.prototype.formatResult = function(object) {
-  if (object.path_with_namespace) {
-    return `<div class='project-result'> <div class='project-name'>${object.name}</div> <div class='project-path'>${object.path_with_namespace}</div> </div>`;
-  } else if (object.path) {
-    return `<div class='group-result'> <div class='group-name'>${object.name}</div> <div class='group-path'>${object.path}</div> </div>`;
-  } else {
-    return `<div class='group-result'> <div class='group-name'>${__(
-      'All',
-    )}</div> <div class='group-path'>${__('All groups and projects')}</div> </div>`;
+const formatResult = selectedItem => {
+  if (selectedItem.path_with_namespace) {
+    return `<div class='project-result'> <div class='project-name'>${selectedItem.name}</div> <div class='project-path'>${selectedItem.path_with_namespace}</div> </div>`;
+  } else if (selectedItem.path) {
+    return `<div class='group-result'> <div class='group-name'>${selectedItem.name}</div> <div class='group-path'>${selectedItem.path}</div> </div>`;
   }
+  return `<div class='group-result'> <div class='group-name'>${__(
+    'All',
+  )}</div> <div class='group-path'>${__('All groups and projects')}</div> </div>`;
 };
 
-AdminEmailSelect.prototype.formatSelection = function(object) {
-  if (object.path_with_namespace) {
-    return sprintf(__('Project: %{name}'), { name: object.name });
-  } else if (object.path) {
-    return sprintf(__('Group: %{name}'), { name: object.name });
-  } else {
-    return __('All groups and projects');
+const formatSelection = selectedItem => {
+  if (selectedItem.path_with_namespace) {
+    return sprintf(__('Project: %{name}'), { name: selectedItem.name });
+  } else if (selectedItem.path) {
+    return sprintf(__('Group: %{name}'), { name: selectedItem.name });
   }
+  return __('All groups and projects');
 };
 
-export default AdminEmailSelect;
+const AdminEmailSelect = () => {
+  $('.ajax-admin-email-select').each((i, select) =>
+    $(select).select2({
+      placeholder: __('Select group or project'),
+      multiple: $(select).hasClass('multiselect'),
+      minimumInputLength: 0,
+      query(query) {
+        const groupsFetch = Api.groups(query.term, {});
+        const projectsFetch = Api.projects(query.term, {
+          order_by: 'id',
+          membership: false,
+        });
+        return Promise.all([projectsFetch, groupsFetch]).then(([projects, groups]) => {
+          const all = {
+            id: 'all',
+          };
+          const data = [all].concat(groups, projects);
+          return query.callback({
+            results: data,
+          });
+        });
+      },
+      id(object) {
+        if (object.path_with_namespace) {
+          return `project-${object.id}`;
+        } else if (object.path) {
+          return `group-${object.id}`;
+        }
+        return 'all';
+      },
+      formatResult(...args) {
+        return formatResult(...args);
+      },
+      formatSelection(...args) {
+        return formatSelection(...args);
+      },
+      dropdownCssClass: 'ajax-admin-email-dropdown',
+      escapeMarkup(m) {
+        return m;
+      },
+    }),
+  );
+};
+
+export default () =>
+  import(/* webpackChunkName: 'select2' */ 'select2/select2')
+    .then(AdminEmailSelect)
+    .catch(() => {});