App crashes when unable to connect to API

W/System.err: java.net.UnknownHostException: Unable to resolve host "dev.api.flat.kubernetes.tobiasz.memleak.pl": No address associated with hostname
W/System.err:     at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:141)
W/System.err:     at java.net.Inet6AddressImpl.lookupAllHostAddr(Inet6AddressImpl.java:90)
W/System.err:     at java.net.InetAddress.getAllByName(InetAddress.java:787)
W/System.err:     at okhttp3.Dns$1.lookup(Dns.java:39)
W/System.err:     at okhttp3.internal.connection.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:185)
W/System.err:     at okhttp3.internal.connection.RouteSelector.nextProxy(RouteSelector.java:149)
W/System.err:     at okhttp3.internal.connection.RouteSelector.next(RouteSelector.java:84)
W/System.err:     at okhttp3.internal.connection.StreamAllocation.findConnection(StreamAllocation.java:213)
W/System.err:     at okhttp3.internal.connection.StreamAllocation.findHealthyConnection(StreamAllocation.java:134)
W/System.err:     at okhttp3.internal.connection.StreamAllocation.newStream(StreamAllocation.java:113)
W/System.err:     at okhttp3.internal.connection.ConnectInterceptor.intercept(ConnectInterceptor.java:42)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
W/System.err:     at okhttp3.internal.cache.CacheInterceptor.intercept(CacheInterceptor.java:93)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
W/System.err:     at okhttp3.internal.http.BridgeInterceptor.intercept(BridgeInterceptor.java:93)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
W/System.err:     at okhttp3.internal.http.RetryAndFollowUpInterceptor.intercept(RetryAndFollowUpInterceptor.java:125)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:147)
W/System.err:     at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.java:121)
W/System.err:     at okhttp3.RealCall.getResponseWithInterceptorChain(RealCall.java:200)
W/System.err:     at okhttp3.RealCall.execute(RealCall.java:77)
W/System.err:     at pl.rpieja.flat.api.FlatAPI.login(FlatAPI.kt:33)
W/System.err:     at pl.rpieja.flat.tasks.AsyncLogin$1.invoke(AsyncLogin.kt:9)
W/System.err:     at pl.rpieja.flat.tasks.AsyncLogin$1.invoke(AsyncLogin.kt:5)
W/System.err:     at pl.rpieja.flat.tasks.AsyncRequest.doInBackground(AsyncRequest.kt:18)
W/System.err:     at pl.rpieja.flat.tasks.AsyncRequest.doInBackground(AsyncRequest.kt:9)
W/System.err:     at android.os.AsyncTask$2.call(AsyncTask.java:333)
W/System.err:     at java.util.concurrent.FutureTask.run(FutureTask.java:266)
W/System.err:     at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:245)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1162)
W/System.err:     at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:636)
W/System.err:     at java.lang.Thread.run(Thread.java:764)
W/System.err: Caused by: android.system.GaiException: android_getaddrinfo failed: EAI_NODATA (No address associated with hostname)
W/System.err:     at libcore.io.Linux.android_getaddrinfo(Native Method)
W/System.err:     at libcore.io.ForwardingOs.android_getaddrinfo(ForwardingOs.java:58)
W/System.err:     at java.net.Inet6AddressImpl.lookupHostByName(Inet6AddressImpl.java:122)
W/System.err: 	... 33 more
E/AndroidRuntime: FATAL EXCEPTION: main
                  Process: pl.rpieja.flat.debug, PID: 11694
                  kotlin.KotlinNullPointerException
                      at pl.rpieja.flat.activity.LoginActivity$onCreate$1$1.invoke(LoginActivity.kt:43)
                      at pl.rpieja.flat.activity.LoginActivity$onCreate$1$1.invoke(LoginActivity.kt:17)
                      at pl.rpieja.flat.tasks.AsyncRequest.onPostExecute(AsyncRequest.kt:30)
                      at android.os.AsyncTask.finish(AsyncTask.java:695)
                      at android.os.AsyncTask.-wrap1(Unknown Source:0)
                      at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:712)
                      at android.os.Handler.dispatchMessage(Handler.java:105)
                      at android.os.Looper.loop(Looper.java:164)
                      at android.app.ActivityThread.main(ActivityThread.java:6809)
                      at java.lang.reflect.Method.invoke(Native Method)
                      at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)