Incomplete type definition for signInFailure callback return value (TypeScript)

The documentation says that the valid return type for signInFailure callback is Promise<void>|void but the type definition defines only Promise<void>.

Describe your environment

• Operating System version: Linux
• IDE: Visual Studio Code 1.50.1
• TypeScript: 3.9.7
• Firebase UI version: 4.7.0 (via react-firebaseui 4.1.0)
• Firebase SDK version: 7.24.0

Steps to reproduce:

Write the following code in IDE:

const firebaseUiConfig: firebaseui.auth.Config = {
  callbacks: {
    signInFailure: (error) => {
      console.log("failure");
    },
  }
};

Expected result:

No errors.

Actual result:

IDE gives error:

Type '(error: AuthUIError) => void' is not assignable to type '(error: AuthUIError) => Promise<void>'.
Type 'void' is not assignable to type 'Promise<void>'.ts(2322)

[bojeil-google]

Oops, this slipped through the cracks. Sorry about that. The fix is merged. We will push the release next week with the fix. FYI: @xil222

[apaatsio]

@Rafarel Just return an empty Promise

const firebaseUiConfig: firebaseui.auth.Config = {
  callbacks: {
    signInFailure: (error) => {
      console.log("failure");
      return Promise.resolve();
    },
  }
};