Add error message when reverse routing using gorillamux happens before boot

Former-commit-id: 96dd812a16338824474ba1be0db18c486b2ebc0d

adaptors/gorillamux/_example/main.go

@@ -43,9 +43,18 @@ func main() {
 		games.Post("/{gameID:[0-9]+}/clans/{clanPublicID:[0-9]+}/memberships/demote", h)
 	}
 
-	app.Get("/anything/{anythingparameter:.*}", func(ctx *iris.Context) {
+	myroute := app.Get("/anything/{anythingparameter:.*}", func(ctx *iris.Context) {
 		s := ctx.Param("anythingparameter")
 		ctx.Writef("The path after /anything is: %s", s)
+	}) // .ChangeName("myroute")
+
+	app.Get("/reverse_myroute", func(ctx *iris.Context) {
+		// reverse routing snippet using templates:
+		// https://github.com/kataras/iris/tree/v6/adaptors/view/_examples/template_html_3 (gorillamux)
+		// https://github.com/kataras/iris/tree/v6/adaptors/view/_examples/template_html_4 (httprouter)
+
+		myrouteRequestPath := app.Path(myroute.Name(), "anythingparameter", "something/here")
+		ctx.Writef("Should be '/anything/something/here': %s", myrouteRequestPath)
 	})
 
 	p := app.Party("mysubdomain.")

adaptors/gorillamux/gorillamux.go

@@ -64,9 +64,15 @@ func New() iris.Policies {
 			//  {{ url "providerLink" "provider" "facebook"}}
 			// 	for a path: "/auth/{provider}" with name 'providerLink'
 			URLPath: func(r iris.RouteInfo, args ...string) string {
+				if router == nil {
+					logger(iris.ProdMode, "gorillamux' reverse routing 'URLPath' should be called after Boot/Listen/Serve")
+					return ""
+				}
+
 				if r == nil {
 					return ""
 				}
+
 				if gr := router.Get(r.Name()); gr != nil {
 					u, err := gr.URLPath(args...)
 					if err != nil {

adaptors/gorillamux/gorillamux_test.go

@@ -17,6 +17,6 @@ func TestRouteURLPath(t *testing.T) {
 	expected := "/profile/42/iris-go/something"
 
 	if got := app.Path("profile", "user_id", 42, "ref", "iris-go", "anything", "something"); got != expected {
-		t.Fatalf("httprouter's reverse routing 'URLPath' error:  expected %s but got %s", expected, got)
+		t.Fatalf("gorillamux' reverse routing 'URLPath' error:  expected %s but got %s", expected, got)
 	}
 }