Fix crash when clicking fast on back key on the Add account screen.

appnav/src/main/kotlin/io/element/android/appnav/NotLoggedInFlowNode.kt

@@ -57,6 +57,7 @@ class NotLoggedInFlowNode(
 
     interface Callback : Plugin {
         fun navigateToBugReport()
+        fun onDone()
     }
 
     private val callback: Callback = callback()
@@ -83,6 +84,10 @@ class NotLoggedInFlowNode(
                     override fun navigateToBugReport() {
                         callback.navigateToBugReport()
                     }
+
+                    override fun onDone() {
+                        callback.onDone()
+                    }
                 }
                 loginEntryPoint.createNode(
                     parentNode = this,

appnav/src/main/kotlin/io/element/android/appnav/RootFlowNode.kt

@@ -243,6 +243,10 @@ class RootFlowNode(
                     override fun navigateToBugReport() {
                         backstack.push(NavTarget.BugReport)
                     }
+
+                    override fun onDone() {
+                        backstack.pop()
+                    }
                 }
                 val params = NotLoggedInFlowNode.Params(
                     loginParams = navTarget.params,