diff --git a/lib/shared/unshim-utils.js b/lib/shared/unshim-utils.js
--- a/lib/shared/unshim-utils.js
+++ b/lib/shared/unshim-utils.js
@@ -45,7 +45,7 @@
   return { ...messageStore, messages };
 }
 
-const localUnshimTypes = new Set([
+const localUnshimTypes: Set<MessageType> = new Set([
   messageTypes.IMAGES,
   messageTypes.LEGACY_UPDATE_RELATIONSHIP,
   messageTypes.CREATE_SIDEBAR,