Echo Bot showing object reference error

Describe the issue
When executing the code on my local machine, it displays the error message: 'Object reference not set to an instance of an object.

Code Snippet
var botInternalHostingProtocol = "https";
if (appSettings.UseLocalDevSettings) - The error displays here.
{
// if running locally with ngrok
// the call signalling and notification will use the same internal and external ports
// because you cannot receive requests on the same tunnel with different ports

 // calls come in over 443 (external) and route to the internally hosted port: BotCallingInternalPort
 botInternalHostingProtocol = "http";

 builder.Services.PostConfigure<AppSettings>(options =>
 {
     options.BotInstanceExternalPort = 443;
     options.BotInternalPort = appSettings.BotCallingInternalPort;

 });

}
else
{
//appSettings.MediaDnsName = appSettings.ServiceDnsName;
builder.Services.PostConfigure(options =>
{
options.MediaDnsName = appSettings.ServiceDnsName;
});
}

Expected behavior
We have to execute and run the Echobot.

Start with the Echobot startup code containing the UseLocalDevSettings branch and inspect how appSettings is initialized before that condition. Reproduce the local run, identify which reference is null, and verify that the Echobot executes successfully with the expected local settings.