[#2] add LenientNavHostFragment

bottom-nav-watson/src/main/kotlin/bottom_nav_watson/BottomNavWatson.kt

@@ -263,7 +263,7 @@ private fun AppCompatActivity.obtainNavHostFragment(
     // but it starts to corrupt the back stack when Don't keep activities is enabled, which is avoided by
     // calling NavHostFragment.create(graphResId) and setting as the start destination of the graph -in the xml
     // declaration- an empty fragment.
-    val navHostFragment = NavHostFragment.create(graphResId)
+    val navHostFragment = LenientNavHostFragment.create(graphResId)
     fragmentManager.beginTransaction()
         .add(containerId, navHostFragment, fragmentTag)
         .commitNow()

bottom-nav-watson/src/main/kotlin/bottom_nav_watson/LenientNavHostFragment.kt

@@ -0,0 +1,36 @@
+package bottom_nav_watson
+
+import android.os.Bundle
+import androidx.navigation.fragment.NavHostFragment
+
+/**
+ * We need to subclass NavHostFragment to try/catch the call to super::onDestroyView
+ * as it throws an IllegalStateException when a deep link is launched starting from version
+ * 2.3.0 of the navigation component. Specifically, it crashes when the NavHostFragment
+ * tries to dispose itself by finding its associated NavController and there is none.
+ */
+class LenientNavHostFragment : NavHostFragment() {
+
+    override fun onDestroyView() {
+        try {
+            super.onDestroyView()
+        } catch (e: IllegalStateException) {
+            // We only sallow the exception when it contains the message related with the issue that we know.
+            // Otherwise we rethrow, this is brittle as it ties the implementation to a private reporting message error,
+            // but we prefer this way to avoid hiding unrelated exceptions.
+            if (e.message?.contains("does not have a NavController set") == false) {
+                throw e
+            }
+        }
+    }
+
+    companion object {
+        // We need to duplicate here the key as it's a private field in the library, which is brittle but it is what it is.
+        private const val KEY_GRAPH_ID = "android-support-nav:fragment:graphId"
+
+        fun create(graphResId: Int): NavHostFragment = LenientNavHostFragment().apply {
+            arguments = Bundle().apply { putInt(KEY_GRAPH_ID, graphResId) }
+        }
+    }
+
+}