Fix bugs when selecting a file crash when a webview widget is reopened

android/src/main/java/com/pichillilorenzo/flutter_inappbrowser/InAppBrowserFlutterPlugin.java

 package com.pichillilorenzo.flutter_inappbrowser;
 
+import android.net.Uri;
 import android.os.Build;
+import android.webkit.ValueCallback;
 
 import io.flutter.plugin.common.MethodChannel;
 import io.flutter.plugin.common.PluginRegistry;
@@ -15,6 +17,8 @@ public class InAppBrowserFlutterPlugin implements FlutterPlugin {
   public static InAppBrowser inAppBrowser;
   public static MyCookieManager myCookieManager;
   public static CredentialDatabaseHandler credentialDatabaseHandler;
+  public static ValueCallback<Uri[]> uploadMessageArray;
+
 
   public InAppBrowserFlutterPlugin() {}
 
@@ -61,5 +65,6 @@ public class InAppBrowserFlutterPlugin implements FlutterPlugin {
       credentialDatabaseHandler.dispose();
       credentialDatabaseHandler = null;
     }
+    uploadMessageArray = null;
   }
 }

android/src/main/java/com/pichillilorenzo/flutter_inappbrowser/InAppWebView/InAppWebChromeClient.java

@@ -44,7 +44,6 @@ public class InAppWebChromeClient extends WebChromeClient implements PluginRegis
     private PluginRegistry.Registrar registrar;
     private FlutterWebView flutterWebView;
     private InAppBrowserActivity inAppBrowserActivity;
-  private ValueCallback<Uri[]> mUploadMessageArray;
     private ValueCallback<Uri> mUploadMessage;
     private final static int FILECHOOSER_RESULTCODE = 1;
 
@@ -520,7 +519,7 @@ public class InAppWebChromeClient extends WebChromeClient implements PluginRegis
     public boolean onShowFileChooser(
             WebView webView, ValueCallback<Uri[]> filePathCallback,
             FileChooserParams fileChooserParams) {
-    mUploadMessageArray = filePathCallback;
+        InAppBrowserFlutterPlugin.uploadMessageArray = filePathCallback;
         try {
             Intent contentSelectionIntent = new Intent(Intent.ACTION_GET_CONTENT);
             contentSelectionIntent.addCategory(Intent.CATEGORY_OPENABLE);
@@ -543,10 +542,10 @@ public class InAppWebChromeClient extends WebChromeClient implements PluginRegis
     @TargetApi(Build.VERSION_CODES.LOLLIPOP)
     @Override
     public boolean onActivityResult(int requestCode, int resultCode, Intent data) {
-    if (requestCode == FILECHOOSER_RESULTCODE && (resultCode == RESULT_OK || resultCode == RESULT_CANCELED)) {
-      mUploadMessageArray.onReceiveValue(WebChromeClient.FileChooserParams.parseResult(resultCode, data));
+        if (requestCode == FILECHOOSER_RESULTCODE && (resultCode == RESULT_OK || resultCode == RESULT_CANCELED) && InAppBrowserFlutterPlugin.uploadMessageArray != null) {
+            InAppBrowserFlutterPlugin.uploadMessageArray.onReceiveValue(WebChromeClient.FileChooserParams.parseResult(resultCode, data));
         }
-    return false;
+        return true;
     }
 
     private MethodChannel getChannel() {