Issue: Status code is set to 200 before marshalling data into body inside visit functions, so when an error occurs marshalling the ResponseErrorHandlerFunc cannot set the status code.

Reproduce:

openapi: 3.0.1info:title: error-handler-exampleversion: 1.0.0paths:/api/example:post:operationId: exampleHandlerresponses:200:description: examplecontent:application/json:schema:type: objectproperties:example:type: stringformat: email

package: apigenerate:  gorilla-server: true  strict-server: true  models: trueoutput: generated/gen.go

package mainimport ("context""net/http"api "example.go/generated"openapi_types "github.com/oapi-codegen/runtime/types")type ExampleHandler struct {}func main() {e := &ExampleHandler{}h := api.NewStrictHandlerWithOptions(e, nil, api.StrictHTTPServerOptions{ResponseErrorHandlerFunc: func(w http.ResponseWriter, r *http.Request, err error) {w.WriteHeader(500)},})handler := api.Handler(h)err := http.ListenAndServe(":8080", handler)panic(err)}func (*ExampleHandler) ExampleHandler(ctx context.Context,request api.ExampleHandlerRequestObject) (api.ExampleHandlerResponseObject, error) {email := openapi_types.Email("invalid email")return api.ExampleHandler200JSONResponse{Example: &email,}, nil}

Generated visit function

func (response ExampleHandler200JSONResponse) VisitExampleHandlerResponse(w http.ResponseWriter) error {w.Header().Set("Content-Type", "application/json")w.WriteHeader(200)return json.NewEncoder(w).Encode(response)}

Proposed changes would have the output

func (response ExampleHandler200JSONResponse) VisitExampleHandlerResponse(w http.ResponseWriter) error {if err := json.NewEncoder(w).Encode(response); err != nil {return err}w.Header().Set("Content-Type", "application/json")w.WriteHeader(200)return nil}

fix: allow response error handler to set status code

93a9d39

change the order the visit response body function sets the status codeand content type so if an error occurs during json marshalling theresponse error handler can set the status code