core/vm: Enhance EVM error handling with structured error types

[jtn-dev]

Summary

This PR significantly improves the EVM error handling system by introducing structured error types that provide rich contextual information for debugging.

Changes

• New Error Types: GasError, StackError, MemoryError with detailed context
• Enhanced Messages: Transform "out of gas" → "gas error in SSTORE: required 20000, available 5000"
• Full Testing: Comprehensive unit and integration tests
• Documentation: Complete usage guide and examples
• Backward Compatible: Zero breaking changes

Benefits

• Improved debugging experience for developers
• Type-safe error handling
• Better tooling integration possibilities
• Enhanced monitoring capabilities

Testing

• ✅ All existing tests pass
• ✅ New unit tests for error types
• ✅ Integration tests with real EVM scenarios
• ✅ Performance benchmarks show minimal overhead

Files Modified

• core/vm/errors.go - New structured error types
• core/vm/interpreter.go - Stack error integration
• core/vm/instructions.go - Memory error context
• core/vm/errors_test.go - Unit tests
• core/vm/errors_integration_test.go - Integration tests
• core/vm/README_ERRORS.md - Documentation

[MariusVanDerWijden]

Could you expand a bit on why you think these additional error types are useful?
Especially why do you want to replace the underflow and overflow errors?

[jtn-dev]

Could you expand a bit on why you think these additional error types are useful?

Instead of vague errors, you get specific details:
Old: "stack underflow (1 <=> 2)"
New: "stack error in ADD: required 2 items, available 1"
Code can inspect specific error details programmatically.

Especially why do you want to replace the underflow and overflow errors?

Context matters: Knowing which operation caused the stack error is crucial for debugging
Consistency: All errors follow the same structured pattern
Extensibility: Easy to add more debugging info later
The key improvement: instead of just knowing "something went wrong with the stack," you know "ADD operation failed because it needed 2 stack items but only had 1."