fix: ensure named sprite type is nil-checked before renaming

[aofei]

Fixes goplus/builder#1470

Pull Request Overview

This PR fixes the issue reported in goplus/builder#1470 by ensuring that a named sprite type is properly nil-checked before renaming it.

• Adds a new test case ("WrongCodeWithInvalidType") in rename_test.go to validate the behavior when an invalid sprite type is encountered.
• Updates the spxRenameSpriteResource function in rename.go to include a nil-check for tv.Type and use vfs.HasSpriteType for additional validation.

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
internal/server/rename_test.go	New test case added to check behavior for invalid sprite type cases.
internal/server/rename.go	Updated condition to nil-check tv.Type and validate sprite type using vfs.HasSpriteType.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.58%. Comparing base (6408b54) to head (85b3438).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #52      +/-   ##
==========================================
+ Coverage   66.55%   66.58%   +0.03%     
==========================================
  Files          39       39              
  Lines        6007     6007              
==========================================
+ Hits         3998     4000       +2     
+ Misses       1762     1760       -2     
  Partials      247      247              

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