fix: link github and google (#2626)

packages/hoppscotch-app/helpers/fb/auth.ts

@@ -16,6 +16,7 @@ import {
   signOut,
   linkWithCredential,
   AuthCredential,
+  AuthError,
   UserCredential,
   updateProfile,
   updateEmail,
@@ -239,6 +240,24 @@ export async function linkWithFBCredential(
   return await linkWithCredential(user, credential)
 }
 
+/**
+ * Links account with another account given in a auth/account-exists-with-different-credential error
+ *
+ * @param user - User who has the errors
+ *
+ * @param error - Error caught after trying to login
+ *
+ * @returns Promise of UserCredential
+ */
+export async function linkWithFBCredentialFromAuthError(
+  user: User,
+  error: unknown
+) {
+  // Marked as not null since this function is supposed to be called after an auth/account-exists-with-different-credential error, ie credentials actually exist
+  const credentials = OAuthProvider.credentialFromError(error as AuthError)!
+  return await linkWithCredential(user, credentials)
+}
+
 /**
  * Sends an email with the signin link to the user
  *