check for the null

Summary: This fixes the bug mentioned [here](https://fb.workplace.com/groups/flippersupport/permalink/976743249473000/)

Reviewed By: nikoant

Differential Revision: D24016091

fbshipit-source-id: 1ce49d850b6562fb9f09b9e640185316efc927c6

desktop/app/src/chrome/mainsidebar/sidebarUtils.tsx

@@ -168,7 +168,7 @@ export const PluginSidebarListItem: React.FC<{
       />
       <PluginName
         title={`${getPluginTitle(plugin)} ${plugin.version} ${
-          plugin.details.description ? '- ' + plugin.details.description : ''
+          plugin.details?.description ? '- ' + plugin.details?.description : ''
         }`}>
         {getPluginTitle(plugin)}
       </PluginName>

desktop/app/src/plugin.tsx

@@ -126,7 +126,7 @@ export abstract class FlipperBasePlugin<
   static gatekeeper: string | null = null;
   static entry: string | null = null;
   static isDefault: boolean;
-  static details: PluginDetails;
+  static details: PluginDetails | undefined;
   static keyboardActions: KeyboardActions | null;
   static screenshot: string | null;
   static defaultPersistedState: any;