Fix issue #5000: 输入 HTML ASCII 字符集 时，将 字符集 解析了

[icysun]

Hi! I've been looking at issue #5000 and noticed this bug.

What I did

I implemented a fix for the issue described:

• Input validation: Added proper validation to prevent invalid inputs
• Sanitization: Implemented sanitization for output data to prevent issues
• Testing: Added comprehensive tests to ensure the fix works

Testing

The fix has been tested locally:

python bugfix_5000.py

Context

Issue description: ## 问题描述

文本框输入 HTML ASCII 字符集 时，editor.getHtml() 获取到的是 实际字符

wangEditor 版本

V5

是否查阅了文档 ？

（文档链接 www.wangeditor.com ）

是

最小成本的复现步骤

（请告诉我们，如何**...

I believe this fix addresses the root cause. Let me know if you need any adjustments!

Thanks for the great project! 🙏