Remove nullability of ClientFactory functions returns

app/src/main/java/com/github/gotify/api/ClientFactory.kt

@@ -39,22 +39,22 @@ internal object ClientFactory {
             arrayOf("clientTokenHeader"),
             "$baseUrl/", sslSettings
         )
-        val tokenAuth = client.apiAuthorizations["clientTokenHeader"] as ApiKeyAuth?
-        tokenAuth!!.apiKey = token
+        val tokenAuth = client.apiAuthorizations["clientTokenHeader"] as ApiKeyAuth
+        tokenAuth.apiKey = token
         return client
     }
 
-    fun versionApi(baseUrl: String, sslSettings: SSLSettings): VersionApi? {
+    fun versionApi(baseUrl: String, sslSettings: SSLSettings): VersionApi {
         return unauthorized(baseUrl, sslSettings).createService(VersionApi::class.java)
     }
 
-    fun userApiWithToken(settings: Settings): UserApi? {
+    fun userApiWithToken(settings: Settings): UserApi {
         return clientToken(settings.url, settings.sslSettings(), settings.token)
             .createService(UserApi::class.java)
     }
 
     private fun defaultClient(
-        authentications: Array<String?>,
+        authentications: Array<String>,
         baseUrl: String,
         sslSettings: SSLSettings
     ): ApiClient {

app/src/main/java/com/github/gotify/init/InitializationActivity.kt

@@ -59,8 +59,8 @@ internal class InitializationActivity : AppCompatActivity() {
 
     private fun tryAuthenticate() {
         ClientFactory.userApiWithToken(settings)
-                ?.currentUser()
-                ?.enqueue(
+                .currentUser()
+                .enqueue(
                     Callback.callInUI(this, { if (it != null) authenticated(it) }) { apiException ->
                         failed(apiException)
                     }
@@ -124,7 +124,7 @@ internal class InitializationActivity : AppCompatActivity() {
         errorCallback: Callback.ErrorCallback
     ) {
         ClientFactory.versionApi(settings.url, settings.sslSettings())
-            ?.version
-            ?.enqueue(Callback.callInUI(this, callback, errorCallback))
+            .version
+            .enqueue(Callback.callInUI(this, callback, errorCallback))
     }
 }

app/src/main/java/com/github/gotify/login/LoginActivity.kt

@@ -102,8 +102,8 @@ internal class LoginActivity : AppCompatActivity() {
 
         try {
             ClientFactory.versionApi(url, tempSslSettings())
-                ?.version
-                ?.enqueue(Callback.callInUI(this, onValidUrl(url), onInvalidUrl(url)))
+                .version
+                .enqueue(Callback.callInUI(this, onValidUrl(url), onInvalidUrl(url)))
         } catch (e: Exception) {
             binding.checkurlProgress.visibility = View.GONE
             binding.checkurl.visibility = View.VISIBLE

app/src/main/java/com/github/gotify/service/WebSocketService.kt

@@ -112,8 +112,8 @@ internal class WebSocketService : Service() {
             getString(R.string.websocket_closed), getString(R.string.websocket_reconnect)
         )
         ClientFactory.userApiWithToken(settings)
-            ?.currentUser()
-            ?.enqueue(Callback.call({ doReconnect() }) { exception ->
+            .currentUser()
+            .enqueue(Callback.call({ doReconnect() }) { exception ->
                 if (exception.code == 401) {
                     showForegroundNotification(
                         getString(R.string.user_action),