simplesmente usei o template default de api na IDE como mostra na aula e ao abrir o arquivo program.cs já vem esse erro:
Severity Code Description Project File Line Suppression State
Error CS1061 'IServiceCollection' does not contain a definition for 'AddSwaggerGen' and no accessible extension method 'AddSwaggerGen' accepting a first argument of type 'IServiceCollection' could be found (are you missing a using directive or an assembly reference?) filmesApi C:\Users\karl\projetos\filmesApi\filmesApi\Program.cs 8 Active