fix a possible panic because of taking the address of nil

Signed-off-by: Abirdcfly <[email protected]>

Kubernetes-commit: f8a9c32a47f5d12d1baabe90a62e8637d47110d3

Author: Abirdcfly

tools/clientcmd/auth_loaders.go

@@ -51,10 +51,10 @@ func (a *PromptingAuthLoader) LoadAuth(path string) (*clientauth.Info, error) {
 	// Prompt for user/pass and write a file if none exists.
 	if _, err := os.Stat(path); os.IsNotExist(err) {
 		authPtr, err := a.Prompt()
-		auth := *authPtr
 		if err != nil {
 			return nil, err
 		}
+		auth := *authPtr
 		data, err := json.Marshal(auth)
 		if err != nil {
 			return &auth, err