SignIn callback runs before OAuth account creation.

[devdatkumar]

async signIn({ user, account }) {
      if (user.id && account?.provider !== "credentials") {
        // Check if the user is already verified
        const [existingUser] = await db
          .select({ emailVerified: users.emailVerified })
          .from(users)
          .where(eq(users.id, user.id))
          .limit(1);

        // Update emailVerified if not already verified
        if (existingUser && !existingUser.emailVerified) {
          console.log("updating existing user");
          await db
            .update(users)
            .set({ emailVerified: new Date() })
            .where(eq(users.id, user.id));
        }
      }
      return true;
    },

On the first run, using OAuth, the existing user throws undefined.
because SignIn callback runs before account/user creation.
but work on second run, since account and user data is already available, so it doesn't throw error.

 POST /auth/signin 303 in 664ms
Query: select "account"."userId", "account"."type", "account"."provider", "account"."provider_account_id", "account"."refresh_token", "account"."access_token", "account"."expires_at", "account"."token_type", "account"."scope", "account"."id_token", "account"."session_state", "user"."id", "user"."name", "user"."email", "user"."password", "user"."image", "user"."role", "user"."email_verified" from "account" inner join "user" on "account"."userId" = "user"."id" where ("account"."provider" = $1 and "account"."provider_account_id" = $2) -- params: ["google", "114363806152719312166"]  
Query: select "email_verified" from "user" where "user"."id" = $1 limit $2 -- params: ["08323a4e-f1a1-4134-bf49-c427e34d05d0", 1]

existing user: undefined

... more Queries