Fix extension API not having all the correct types (#7263)

Signed-off-by: Sebastian Malton <sebastian@malton.name>

packages/extension-api/package.json

@@ -39,6 +39,7 @@
     "style-loader": "^3.3.1",
     "ts-loader": "^9.4.2",
     "ts-node": "^10.9.1",
+    "typed-emitter": "^2.1.0",
     "typedoc": "0.23.25",
     "typedoc-plugin-markdown": "^3.13.6",
     "typescript": "^4.9.5",