Merge pull request #1050 from rsydor/patch-1

Fix Android Sometimes crash after close webpage and return to platform code.

android/src/main/java/com/pichillilorenzo/flutter_inappwebview/in_app_webview/InAppWebView.java

@@ -1300,8 +1300,7 @@ final public class InAppWebView extends InputAwareWebView implements InAppWebVie
                         public void run() {
                           InputMethodManager imm =
                                   (InputMethodManager) getContext().getSystemService(INPUT_METHOD_SERVICE);
-                          if (imm != null && !imm.isAcceptingText()) {
-
+                          if (containerView != null && imm != null && !imm.isAcceptingText()) {
                             imm.hideSoftInputFromWindow(
                                     containerView.getWindowToken(), InputMethodManager.HIDE_NOT_ALWAYS);
                           }