Kotlin Google 登录 关闭登录对话框时出现 ApiException 12501

我已经成功地实现了谷歌登录，它工作得很好，当我真正完成整个登录过程时，没有例外.

但是，如果我点击谷歌登录按钮，然后点击后退按钮关闭对话框，我不知何故会出现以下错误:

Caused by: com.google.android.gms.tasks.RuntimeExecutionException: com.google.android.gms.common.api.ApiException: 12501: at com.google.android.gms.tasks.zzu.getResult(Unknown Source:17)

which points me to this piece of code:

if (requestCode == RC_SIGN_IN) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            try {
                val account = task.result
                firebaseAuthWithGoogle(account)
            } catch (e: ApiException) {
                Toast.makeText(this, "Google Sign In Failed", Toast.LENGTH_SHORT).show()
            }
        }

specifically on the val account = task.result line.

My question is, shouldn't it handle it by himself via the catch and print out the toast? Why is the whole app crashing instead?

Here is my whole SignInActivity:

import android.content.Context
import android.content.Intent
import android.os.Bundle
import android.support.design.widget.BottomSheetDialog
import android.support.v7.app.AppCompatActivity
import android.view.View
import android.widget.Toast
import com.dancam.subscriptions.ActiveSubscriptions.SubscriptionsMain
import com.dancam.subscriptions.R.id.google_signin_button
import com.dancam.subscriptions.R.id.signin_progressbar
import com.google.android.gms.auth.api.signin.GoogleSignIn
import com.google.android.gms.auth.api.signin.GoogleSignInAccount
import com.google.android.gms.auth.api.signin.GoogleSignInClient
import com.google.android.gms.auth.api.signin.GoogleSignInOptions
import com.google.android.gms.common.SignInButton
import com.google.android.gms.common.api.ApiException
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.FirebaseUser
import com.google.firebase.auth.GoogleAuthProvider
import kotlinx.android.synthetic.main.reset_password_dialog.view.*
import kotlinx.android.synthetic.main.sign_dialog.view.*
import kotlinx.android.synthetic.main.signin.*
import org.jetbrains.anko.defaultSharedPreferences
import org.jetbrains.anko.sdk25.coroutines.onClick

class SignInActivity: AppCompatActivity() {
    private var mAuth: FirebaseAuth? = null
    private var mGoogleSignInClient: GoogleSignInClient? = null

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.signin)

        val gso = GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.default_web_client_id))
                .requestEmail()
                .build()

        mGoogleSignInClient = GoogleSignIn.getClient(this, gso)
        mAuth = FirebaseAuth.getInstance()

        google_signin_button.setSize(SignInButton.SIZE_WIDE)
        google_signin_button.setOnClickListener { signIn() }
    }

    override fun onStart() {
        super.onStart()
        val currentUser = mAuth?.currentUser

        if (currentUser!=null) loggedIn(currentUser)
    }

    private fun signIn() {
        val signInIntent = mGoogleSignInClient?.signInIntent
        startActivityForResult(signInIntent, RC_SIGN_IN)
        signin_progressbar.visibility = View.VISIBLE
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)

        if (requestCode == RC_SIGN_IN) {
            val task = GoogleSignIn.getSignedInAccountFromIntent(data)
            try {
                val account = task.result
                firebaseAuthWithGoogle(account)
            } catch (e: ApiException) {
                Toast.makeText(this, "Google Sign In Failed", Toast.LENGTH_SHORT).show()
            }
        }
    }

    private fun firebaseAuthWithGoogle(acct: GoogleSignInAccount) {
        val credential = GoogleAuthProvider.getCredential(acct.idToken, null)
        mAuth?.signInWithCredential(credential)
                ?.addOnCompleteListener {
                    if (it.isSuccessful) {
                        signin_progressbar.visibility = View.GONE
                        val user = mAuth?.currentUser
                        loggedIn(user)
                    } else {
                        signin_progressbar.visibility = View.GONE
                        Toast.makeText(this, "Authentication Failed", Toast.LENGTH_SHORT).show()
                        loggedIn(null)
                    }
                }
    }

    fun onSignUpClicked(args: View) {
        val view = layoutInflater.inflate(R.layout.sign_dialog, null)
        val dialog = BottomSheetDialog(this)
        dialog.setContentView(view)
        dialog.show()

        view.register_button.setOnClickListener {
            val email = view.signup_email.text.toString()
            val password = view.signup_password.text.toString()
            val password2 = view.signup_password2.text.toString()

            if (password == password2) {
                mAuth?.createUserWithEmailAndPassword(email, password)
                        ?.addOnCompleteListener {
                            if (it.isSuccessful) {
                                //sign in success updateUI
                                val user = mAuth?.currentUser
                                loggedIn(user)
                            } else {
                                // signin failed
                                //TODO: translate
                                Toast.makeText(this, "Authentication Failed", Toast.LENGTH_SHORT).show()
                                loggedIn(null)
                            }
                        }
            } else {
                //TODO: translate
                Toast.makeText(this, "Passwords do not match", Toast.LENGTH_LONG).show()
            }
        }
    }

    fun onSignInClicked(args: View) {
        val view = layoutInflater.inflate(R.layout.sign_dialog, null)
        val dialog = BottomSheetDialog(this)

        //TODO: translate
        view.dialog_textview.text = "Sign In"
        view.signup_password2.visibility = View.GONE

        dialog.setContentView(view)
        dialog.show()

        //TODO: translate
        view.register_button.text = "Sign In"
        view.register_button.setOnClickListener {
            val email = view.signup_email.text.toString()
            val password = view.signup_password.text.toString()

            mAuth?.signInWithEmailAndPassword(email, password)
                    ?.addOnCompleteListener {
                        if (it.isSuccessful) {
                            val user = mAuth?.currentUser
                            loggedIn(user)
                        } else {
                            //TODO: translate
                            Toast.makeText(this, "Sign In Failed", Toast.LENGTH_LONG).show()
                            view.forgotten_password.visibility = View.VISIBLE

                            view.forgotten_password.onClick {
                                dialog.dismiss()
                                resetDialog()
                            }
                        }
                    }
        }
    }

    private fun resetDialog() {
        val resetView = layoutInflater.inflate(R.layout.reset_password_dialog, null)
        val resetDialog = BottomSheetDialog(this)
        resetDialog.setContentView(resetView)
        resetDialog.show()

        resetView.send_reset_email.setOnClickListener {
            resetView.send_reset_email.isClickable = false
            val email = resetView.reset_email.text.toString()
            mAuth?.sendPasswordResetEmail(email)
                    ?.addOnSuccessListener {
                        //TODO: translate
                        Toast.makeText(this, "Email Sent", Toast.LENGTH_SHORT).show()
                        resetDialog.dismiss()
                    }
        }
    }

    private fun loggedIn(user: FirebaseUser?) {
        startActivity(Intent(this, SubscriptionsMain::class.java))
        finish()
    }

    fun onSkipClicked(args:View) {
        loggedIn(null)
    }

    companion object {
        const val RC_SIGN_IN = 0000    }
}