NSwag command line to generate cs client issue

[peterhoang]

I'm trying to generate the C# client files after the build of my solution so I have the following in my main csproj file:

<Target Name="NSwag" BeforeTargets="AfterBuild">
      <Exec ConsoleToMSBuild="true" ContinueOnError="true" Command="$(NSwagExe_Net80) run nswag.json /variables:Configuration=$(Configuration),CSharpOutputPath=$(MSBuildThisFileDirectory)..\Client">
          <Output TaskParameter="ExitCode" PropertyName="NSwagExitCode" />
          <Output TaskParameter="ConsoleOutput" PropertyName="NSwagOutput" />
      </Exec>

      <Message Text="$(NSwagOutput)" Condition="'$(NSwagExitCode)' == '0'" Importance="low" />
      <Error Text="$(NSwagOutput)" Condition="'$(NSwagExitCode)' != '0'" />
  </Target>

And the nswag.json:

{
    "runtime": "Net80",
    "defaultVariables": "GeneratedFilesOutputPath=..\\Client",
    "documentGenerator": {
        "aspNetCoreToOpenApi": {
            "project": "Web.Api.csproj",
            "msBuildProjectExtensionsPath": null,            
            "runtime": "",
            "targetFramework": "",
            "noBuild": true,
            "verbose": true,
            "workingDirectory": null,
            "requireParametersWithoutDefault": true,
            "apiGroupNames": null,
            "defaultPropertyNameHandling": "CamelCase",
            "defaultReferenceTypeNullHandling": "Null",
            "defaultDictionaryValueReferenceTypeNullHandling": "NotNull",
            "defaultResponseReferenceTypeNullHandling": "NotNull",
            "defaultEnumHandling": "Integer",
            "flattenInheritanceHierarchy": false,
            "generateKnownTypes": true,
            "generateEnumMappingDescription": false,
            "generateXmlObjects": false,
            "generateAbstractProperties": true,
            "generateAbstractSchemas": true,
            "ignoreObsoleteProperties": false,
            "allowReferencesWithProperties": false,
            "excludedTypeNames": [],
            "serviceHost": null,
            "serviceBasePath": null,
            "serviceSchemes": [],
            "infoTitle": null,
            "infoDescription": null,
            "infoVersion": "1.0.0",
            "documentTemplate": null,
            "documentProcessorTypes": [],
            "operationProcessorTypes": [],
            "typeNameGeneratorType": null,
            "schemaNameGeneratorType": null,
            "contractResolverType": null,
            "serializerSettingsType": null,
            "useDocumentProvider": false,
            "documentName": "v1",
            "aspNetCoreEnvironment": null,
            "createWebHostBuilderMethod": null,
            "startupType": null,
            "allowNullableBodyParameters": true,
            "output": null,
            "outputType": "OpenApi3",
            "newLineBehavior": "Auto",
            "assemblyPaths": [],
            "assemblyConfig": null,
            "referencePaths": [],
            "useNuGetCache": false
        }
    },
    "codeGenerators": {
        "openApiToCSharpClient": {
            "clientBaseClass": null,
            "configurationClass": null,
            "generateClientClasses": true,
            "suppressClientClassesOutput": false,
            "generateClientInterfaces": true,
            "suppressClientInterfacesOutput": false,
            "clientBaseInterface": null,
            "injectHttpClient": true,
            "disposeHttpClient": true,
            "protectedMethods": [],
            "generateExceptionClasses": true,
            "exceptionClass": "SwaggerException",
            "wrapDtoExceptions": true,
            "useHttpClientCreationMethod": false,
            "httpClientType": "System.Net.Http.HttpClient",
            "useHttpRequestMessageCreationMethod": false,
            "useBaseUrl": true,
            "generateBaseUrlProperty": true,
            "generateSyncMethods": false,
            "generatePrepareRequestAndProcessResponseAsAsyncMethods": false,
            "exposeJsonSerializerSettings": false,
            "clientClassAccessModifier": "public",
            "typeAccessModifier": "public",
            "propertySetterAccessModifier": "",
            "generateNativeRecords": false,
            "generateContractsOutput": true,
            "contractsNamespace": "Client",
            "contractsOutputFilePath": "$(GeneratedFilesOutputPath)/Contracts.g.cs",
            "parameterDateTimeFormat": "s",
            "parameterDateFormat": "yyyy-MM-dd",
            "generateUpdateJsonSerializerSettingsMethod": true,
            "useRequestAndResponseSerializationSettings": false,
            "serializeTypeInformation": true,
            "queryNullValue": "",
            "className": "{controller}Client",
            "operationGenerationMode": "SingleClientFromOperationId",
            "additionalNamespaceUsages": [],
            "additionalContractNamespaceUsages": [],
            "generateOptionalParameters": false,
            "generateJsonMethods": true,
            "enforceFlagEnums": false,
            "parameterArrayType": "System.Collections.Generic.List",
            "parameterDictionaryType": "System.Collections.Generic.Dictionary",
            "responseArrayType": "System.Collections.Generic.List",
            "responseDictionaryType": "System.Collections.Generic.Dictionary",
            "wrapResponses": false,
            "wrapResponseMethods": [],
            "generateResponseClasses": true,
            "responseClass": "ClientResponse",
            "namespace": "Client",
            "requiredPropertiesMustBeDefined": true,
            "dateType": "System.DateTime",
            "jsonConverters": null,
            "anyType": "object",
            "dateTimeType": "System.DateTime",
            "timeType": "System.TimeSpan",
            "timeSpanType": "System.TimeSpan",
            "arrayType": "System.Collections.Generic.IList",
            "arrayInstanceType": "System.Collections.Generic.List",
            "dictionaryType": "System.Collections.Generic.IDictionary",
            "dictionaryInstanceType": "System.Collections.Generic.Dictionary",
            "arrayBaseType": "System.Collections.Generic.List",
            "dictionaryBaseType": "System.Collections.Generic.Dictionary",
            "classStyle": "Poco",
            "jsonLibrary": "NewtonsoftJson",
            "generateDefaultValues": true,
            "generateDataAnnotations": true,
            "excludedTypeNames": [],
            "excludedParameterNames": [],
            "handleReferences": false,
            "generateImmutableArrayProperties": false,
            "generateImmutableDictionaryProperties": false,
            "jsonSerializerSettingsTransformationMethod": null,
            "inlineNamedArrays": false,
            "inlineNamedDictionaries": false,
            "inlineNamedTuples": true,
            "inlineNamedAny": false,
            "generateDtoTypes": true,
            "generateOptionalPropertiesAsNullable": false,
            "generateNullableReferenceTypes": false,
            "templateDirectory": null,
            "serviceHost": null,
            "serviceSchemes": null,
            "output": "$(GeneratedFilesOutputPath)/Client.g.cs",
            "newLineBehavior": "Auto"
        }
    }
}

I will get a building error about an exception of a missing config (section) in my appsettings. This is by design as I have guards that throw exceptions when an expected configuration is missing in the appsettings.

Before this post build step, the dotnet web API builds and runs fine.

What am I missing or is the Nswag command line not an option for my situation (which I doubt because loading settings from appsettings is a common practice in the dotnet world)?