Remove default value for languageTag and theme.

features/call/impl/src/main/kotlin/io/element/android/features/call/impl/ui/CallScreenPresenter.kt

@@ -189,6 +189,8 @@ class CallScreenPresenter @AssistedInject constructor(
                         sessionId = inputs.sessionId,
                         roomId = inputs.roomId,
                         clientId = UUID.randomUUID().toString(),
+                        languageTag = null,
+                        theme = null,
                     ).getOrThrow()
                     callWidgetDriver.value = result.driver
                     result.url

features/call/impl/src/main/kotlin/io/element/android/features/call/impl/utils/CallWidgetProvider.kt

@@ -25,8 +25,8 @@ interface CallWidgetProvider {
         sessionId: SessionId,
         roomId: RoomId,
         clientId: String,
-        languageTag: String? = null,
-        theme: String? = null,
+        languageTag: String?,
+        theme: String?,
     ): Result<GetWidgetResult>
 
     data class GetWidgetResult(