optimize code and reduce code cyclomatic complexity (#2737)

* optimize code and reduce code cyclomatic complexity

* optimize if-condtion

Co-authored-by: thinkerou <thinkerou@gmail.com>

binding/form.go

@@ -22,11 +22,9 @@ func (formBinding) Bind(req *http.Request, obj interface{}) error {
 	if err := req.ParseForm(); err != nil {
 		return err
 	}
-	if err := req.ParseMultipartForm(defaultMemory); err != nil {
-		if err != http.ErrNotMultipart {
+	if err := req.ParseMultipartForm(defaultMemory); err != nil && err != http.ErrNotMultipart {
 		return err
 	}
-	}
 	if err := mapForm(obj, req.Form); err != nil {
 		return err
 	}

debug.go

@@ -95,9 +95,7 @@ at initialization. ie. before any route is registered or the router is listening
 }
 
 func debugPrintError(err error) {
-	if err != nil {
-		if IsDebugging() {
+	if err != nil && IsDebugging() {
 		fmt.Fprintf(DefaultErrorWriter, "[GIN-debug] [ERROR] %v\n", err)
 	}
 }
-}