Enables strict mode in nextjs apps (#2354)

- We need this so zod works correctly

Co-authored-by: Peer Richelsen <peeroke@gmail.com>

apps/web/pages/api/integrations/[...args].ts

@@ -1,4 +1,4 @@
-import { NextApiRequest, NextApiResponse } from "next";
+import { NextApiHandler, NextApiRequest, NextApiResponse } from "next";
 
 import appStore from "@calcom/app-store";
 
@@ -26,7 +26,12 @@ const handler = async (req: NextApiRequest, res: NextApiResponse) => {
   try {
     // TODO: Find a way to dynamically import these modules
     // const app = (await import(`@calcom/${appName}`)).default;
-    const handler = appStore[appName].api[apiEndpoint];
+    const app = appStore[appName as keyof typeof appStore];
+    if (!(app && "api" in app && apiEndpoint in app.api))
+      throw new HttpError({ statusCode: 404, message: `API handler not found` });
+
+    const handler = app.api[apiEndpoint as keyof typeof app.api] as NextApiHandler;
+
     if (typeof handler !== "function")
       throw new HttpError({ statusCode: 404, message: `API handler not found` });