fix: update tsconfig for Slack package

packages/slack/tsconfig.json

@@ -1,5 +1,8 @@
 {
   "$schema": "https://json.schemastore.org/tsconfig",
   "extends": "@tsconfig/bun/tsconfig.json",
-  "compilerOptions": {}
+  "compilerOptions": {
+    "lib": ["ESNext", "DOM", "DOM.Iterable"],
+    "noUncheckedIndexedAccess": false
+  }
 }