abort setting proxy when either host or port is not valid

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

app/src/main/java/com/owncloud/android/utils/appConfig/AppConfigManager.kt

@@ -10,6 +10,7 @@ package com.owncloud.android.utils.appConfig
 import android.content.Context
 import android.content.res.Resources
 import android.os.Bundle
+import android.text.TextUtils
 import com.owncloud.android.R
 import com.owncloud.android.lib.common.OwnCloudClientManagerFactory
 import com.owncloud.android.lib.common.utils.Log_OC
@@ -36,7 +37,7 @@ class AppConfigManager(private val context: Context, private val appRestrictions
             context.resources.getInteger(R.integer.proxy_port)
         }
 
-        if (host == null) {
+        if (TextUtils.isEmpty(host) || port == -1) {
             Log_OC.d(tag, "Proxy configuration cannot be found")
             return
         }