Apply some smaller changes

app/src/main/kotlin/com/github/gotify/GotifyApplication.kt

@@ -45,7 +45,6 @@ class GotifyApplication : Application() {
                 Logger.info("Migration of legacy CA cert succeeded")
             } catch (e: IOException) {
                 Logger.error(e, "Migration of legacy CA cert failed")
-                if (legacyCert != null) settings.legacyCert = legacyCert
             }
         }
         super.onCreate()

app/src/main/kotlin/com/github/gotify/login/AdvancedDialog.kt

@@ -14,7 +14,6 @@ internal class AdvancedDialog(
     private val context: Context,
     private val layoutInflater: LayoutInflater
 ) {
-    private lateinit var dialog: AlertDialog
     private lateinit var dialogDoneButton: Button
     private lateinit var binding: AdvancedSettingsDialogBinding
     private var onCheckedChangeListener: CompoundButton.OnCheckedChangeListener? = null
@@ -82,7 +81,7 @@ internal class AdvancedDialog(
         binding.clientCertPasswordEdittext.doOnTextChanged { _, _, _, _ ->
             showPasswordMissing(binding.clientCertPasswordEdittext.text.toString().isEmpty())
         }
-        dialog = MaterialAlertDialogBuilder(context)
+        val dialog = MaterialAlertDialogBuilder(context)
             .setView(binding.root)
             .setTitle(R.string.advanced_settings)
             .setPositiveButton(context.getString(R.string.done), null)

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

@@ -65,7 +65,7 @@ internal class LoginActivity : AppCompatActivity() {
                 copyStreamToFile(fileStream, destinationFile)
 
                 // temporarily store it (don't store to settings until they decide to login)
-                caCertCN = getNameOfCertContent(destinationFile)!!
+                caCertCN = getNameOfCertContent(destinationFile) ?: "unknown"
                 caCertPath = destinationFile.absolutePath
                 advancedDialog.showRemoveCaCertificate(caCertCN!!)
             } catch (e: Exception) {
@@ -220,7 +220,7 @@ internal class LoginActivity : AppCompatActivity() {
     }
 
     private fun getNameOfCertContent(file: File): String? {
-        val ca = CertUtils.parseCertificate(FileInputStream(file))
+        val ca = FileInputStream(file).use { CertUtils.parseCertificate(it) }
         return (ca as X509Certificate).subjectX500Principal.name
     }