Stop create-react-app from opening an extra browser tab (pointed to the wrong port)

src/Microsoft.AspNetCore.SpaServices.Extensions/ReactDevelopmentServer/ReactDevelopmentServerMiddleware.cs

@@ -59,7 +59,8 @@ namespace Microsoft.AspNetCore.SpaServices.ReactDevelopmentServer
 
             var envVars = new Dictionary<string, string>
             {
-                { "PORT", portNumber.ToString() }
+                { "PORT", portNumber.ToString() },
+                { "BROWSER", "none" }, // We don't want create-react-app to open its own extra browser window pointing to the internal dev server port
             };
             var npmScriptRunner = new NpmScriptRunner(
                 sourcePath, npmScriptName, null, envVars);