Edit attributes produce crash

[BishopGIS]

java.lang.NullPointerException
    at com.nextgis.maplibui.activity.ModifyAttributesActivity.saveFeature(ModifyAttributesActivity.java:536)
    at com.nextgis.maplibui.activity.ModifyAttributesActivity.onOptionsItemSelected(ModifyAttributesActivity.java:485)
    at android.app.Activity.onMenuItemSelected(Activity.java:2606)
    at android.support.v4.app.FragmentActivity.onMenuItemSelected(FragmentActivity.java:421)
    at android.support.v7.app.AppCompatActivity.onMenuItemSelected(AppCompatActivity.java:188)
    at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:103)
    at android.support.v7.view.WindowCallbackWrapper.onMenuItemSelected(WindowCallbackWrapper.java:103)
    at android.support.v7.app.ToolbarActionBar$2.onMenuItemClick(ToolbarActionBar.java:69)
    at android.support.v7.widget.Toolbar$1.onMenuItemClick(Toolbar.java:202)
    at android.support.v7.widget.ActionMenuView$MenuBuilderCallback.onMenuItemSelected(ActionMenuView.java:761)
    at android.support.v7.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:810)
    at android.support.v7.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:152)
    at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:957)
    at android.support.v7.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:947)
    at android.support.v7.widget.ActionMenuView.invokeItem(ActionMenuView.java:618)
    at android.support.v7.view.menu.ActionMenuItemView.onClick(ActionMenuItemView.java:155)
    at android.view.View.performClick(View.java:4492)
    at android.view.View$PerformClick.run(View.java:18568)
    at android.os.Handler.handleCallback(Handler.java:733)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:136)
    at android.app.ActivityThread.main(ActivityThread.java:5021)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at java.lang.reflect.Method.invoke(Method.java:515)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:827)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:643)
    at dalvik.system.NativeStart.main(Native Method)