Fix error when combining Message and Image

app/src/main/kotlin/com/github/gotify/messages/ListMessageAdapter.kt

@@ -79,10 +79,12 @@ internal class ListMessageAdapter(
             holder.message.text = message.message.message
         }
         holder.title.text = message.message.title
+        if (message.image != null) {
             picasso.load(Utils.resolveAbsoluteUrl("${settings.url}/", message.image))
                 .error(R.drawable.ic_alarm)
                 .placeholder(R.drawable.ic_placeholder)
                 .into(holder.image)
+        }
 
         val prefs = PreferenceManager.getDefaultSharedPreferences(context)
         val timeFormat = prefs.getString(timeFormatPrefsKey, timeFormatRelative)

app/src/main/kotlin/com/github/gotify/messages/provider/MessageImageCombiner.kt

@@ -10,7 +10,7 @@ internal object MessageImageCombiner {
         messages.forEach {
             val messageWithImage = MessageWithImage()
             messageWithImage.message = it
-            messageWithImage.image = appIdToImage[it.appid]!!
+            messageWithImage.image = appIdToImage[it.appid]
             result.add(messageWithImage)
         }
         return result

app/src/main/kotlin/com/github/gotify/messages/provider/MessageWithImage.kt

@@ -4,5 +4,5 @@ import com.github.gotify.client.model.Message
 
 internal class MessageWithImage {
     lateinit var message: Message
-    lateinit var image: String
+    var image: String? = null
 }