Fix: the disposal exceptions (#2209)

Author: glennawatson

src/ReactiveUI.AndroidSupport/ReactivePagerAdapter.cs

@@ -106,7 +106,7 @@ protected override void Dispose(bool disposing)
         {
             if (disposing)
             {
-                Interlocked.Exchange(ref _inner, Disposable.Empty).Dispose();
+                _inner?.Dispose();
                 _list?.Dispose();
             }
 

src/ReactiveUI.AndroidSupport/ReactiveRecyclerViewAdapter.cs

@@ -91,7 +91,7 @@ protected override void Dispose(bool disposing)
         {
             if (disposing)
             {
-                Interlocked.Exchange(ref _inner, Disposable.Empty).Dispose();
+                _inner?.Dispose();
                 _list?.Dispose();
             }
 

src/ReactiveUI.AndroidX/ReactivePagerAdapter.cs

@@ -106,7 +106,7 @@ protected override void Dispose(bool disposing)
         {
             if (disposing)
             {
-                Interlocked.Exchange(ref _inner, Disposable.Empty).Dispose();
+                _inner?.Dispose();
                 _list?.Dispose();
             }
 

src/ReactiveUI.AndroidX/ReactiveRecyclerViewAdapter.cs

@@ -84,7 +84,7 @@ protected override void Dispose(bool disposing)
         {
             if (disposing)
             {
-                Interlocked.Exchange(ref _inner, Disposable.Empty).Dispose();
+                _inner?.Dispose();
                 _list?.Dispose();
             }