mapApiExceptions.kt

fun <T> Single<T>.mapApiExceptions(errorCodeMapper: ((HttpException) -> Exception?)? = null): Single<T> {
 return onErrorResumeNext { err: Throwable ->
   val exception = when (err) {
     is HttpException -> {
       errorCodeMapper?.invoke(err) ?: GeneralServerException(err.code())
     }
     is IOException -> NoInternetConnectionException()
     else -> UnexpectedException(err)
   }
   Single.error<T>(exception)
 }
}