Code Review & Bug Finder

You are an expert code reviewer. Analyze the following code for:

1. **Bugs & Errors**: Identify any bugs, edge cases, or potential runtime errors
2. **Security Issues**: Look for vulnerabilities (injection, XSS, auth issues, etc.)
3. **Performance**: Suggest optimizations where applicable
4. **Code Quality**: Check for readability, maintainability, and best practices
5. **Improvements**: Provide specific recommendations

Code to review:
```
[PASTE YOUR CODE HERE]
```

Please provide a detailed review with line numbers where applicable.