Click Navigate Up crashes the app when using GitLab to log in

[geniuslittleteddy]

Steps to reproduce:

1. Select GitLab to log in
   
2. Click Navigate Up in the following page
   

Replicate the above steps several times, the app will crash. The crash logs is:

04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: Thread: main, Activity:im.vector.activity.LoginActivity, Exception: kotlin.UninitializedPropertyAccessException: lateinit property toolbar has not been initialized
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at im.vector.activity.VectorAppCompatActivity.getToolbar(VectorAppCompatActivity.kt:72)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at im.vector.activity.FallbackAuthenticationActivity$launchWebView$1.onPageStarted(FallbackAuthenticationActivity.kt:148)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at com.android.webview.chromium.WebViewContentsClientAdapter.onPageStarted(WebViewContentsClientAdapter.java:517)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at org.chromium.android_webview.AwContentsClientCallbackHelper$MyHandler.handleMessage(AwContentsClientCallbackHelper.java:144)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at android.os.Handler.dispatchMessage(Handler.java:102)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at android.os.Looper.loop(Looper.java:154)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at android.app.ActivityThread.main(ActivityThread.java:6077)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at java.lang.reflect.Method.invoke(Native Method)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
04-14 17:34:09.693  4338  4338 E FATAL EXCEPTION: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: FATAL EXCEPTION: main
04-14 17:34:09.696  4338  4338 E AndroidRuntime: Process: com.lavadip.miniVector, PID: 4338
04-14 17:34:09.696  4338  4338 E AndroidRuntime: kotlin.UninitializedPropertyAccessException: lateinit property toolbar has not been initialized
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at im.vector.activity.VectorAppCompatActivity.getToolbar(VectorAppCompatActivity.kt:72)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at im.vector.activity.FallbackAuthenticationActivity$launchWebView$1.onPageStarted(FallbackAuthenticationActivity.kt:148)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at com.android.webview.chromium.WebViewContentsClientAdapter.onPageStarted(WebViewContentsClientAdapter.java:517)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at org.chromium.android_webview.AwContentsClientCallbackHelper$MyHandler.handleMessage(AwContentsClientCallbackHelper.java:144)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at android.os.Handler.dispatchMessage(Handler.java:102)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at android.os.Looper.loop(Looper.java:154)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at android.app.ActivityThread.main(ActivityThread.java:6077)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at java.lang.reflect.Method.invoke(Native Method)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
04-14 17:34:09.696  4338  4338 E AndroidRuntime: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
04-14 17:34:09.698  1572  2346 W ActivityManager:   Force finishing activity com.lavadip.miniVector/im.vector.activity.LoginActivity