Type ‘InAppBrowserOriginal’ is not assignable to type ‘Provider’.
Type ‘InAppBrowserOriginal’ is missing the following properties from type ‘FactoryProvider’: provide, useFactory 
I guess the new version of in-app-browser had something changed.
I solved this problem by uninstalling the latest version and installed the older version.
npm uninstall --save @ionic-native/in-app-browser npm install --save @ionic-native/in-app-browser@^4.17.0
I hope this solution help you.
I had the same problem and it worked.