From 6e0b32e4b86d950dd2a879b7a80a57c66481b28c Mon Sep 17 00:00:00 2001
From: "Afshin T. Darian" <git@darian.af>
Date: Mon, 23 Dec 2019 16:16:22 +0000
Subject: [PATCH] Fix strict null check errors.

---
 packages/application-extension/src/index.tsx | 4 ++--
 packages/application/src/frontend.ts         | 2 +-
 packages/filebrowser-extension/src/index.ts  | 3 ++-
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/packages/application-extension/src/index.tsx b/packages/application-extension/src/index.tsx
index ce75423bb774..14e5fabd7cdf 100644
--- a/packages/application-extension/src/index.tsx
+++ b/packages/application-extension/src/index.tsx
@@ -282,10 +282,10 @@ const tree: JupyterFrontEndPlugin<JupyterFrontEnd.ITreeResolver> = {
           const treeMatch = args.path.match(treePattern);
           const workspaceMatch = args.path.match(workspacePattern);
           const match = treeMatch || workspaceMatch;
-          const file = match ? decodeURI(match[1]) : undefined;
+          const file = match ? decodeURI(match[1]) : '';
           const workspace = PathExt.basename(resolver.name);
           const query = URLExt.queryStringToObject(args.search ?? '');
-          const browser = query['file-browser-path'];
+          const browser = query['file-browser-path'] || '';
 
           // Remove the file browser path from the query string.
           delete query['file-browser-path'];
diff --git a/packages/application/src/frontend.ts b/packages/application/src/frontend.ts
index ee07b75f5efc..b615b0459a6c 100644
--- a/packages/application/src/frontend.ts
+++ b/packages/application/src/frontend.ts
@@ -334,7 +334,7 @@ export namespace JupyterFrontEnd {
   export namespace ITreeResolver {
     /**
      * The browser and file paths if the tree resolver encountered and handled
-     * a tree URL or `null` if not.
+     * a tree URL or `null` if not. Empty string paths should be ignored.
      */
     export type Paths = { browser: string; file: string } | null;
   }
diff --git a/packages/filebrowser-extension/src/index.ts b/packages/filebrowser-extension/src/index.ts
index 198668e3b695..514c4317c12a 100644
--- a/packages/filebrowser-extension/src/index.ts
+++ b/packages/filebrowser-extension/src/index.ts
@@ -230,7 +230,8 @@ async function activateFactory(
       manager: docManager,
       driveName: options.driveName || '',
       refreshInterval: options.refreshInterval,
-      state: options.state === null ? undefined : options.state || state
+      state:
+        options.state === null ? undefined : options.state || state || undefined
     });
     const restore = options.restore;
     const widget = new FileBrowser({ id, model, restore });