Panic on Header Validation Failure in Block Production #2182

Description

In the publishBlock method of the block manager, there's a TODO comment suggesting that header validation failure should trigger a panic. Currently, when a newly produced header fails ValidateBasic(), it only logs an error and continues execution. This is problematic because:

1. A freshly produced header should never fail basic validation
2. If it does fail, it indicates a serious bug in the block production logic
3. Continuing execution with an invalid header could lead to undefined behavior and serious issues.

Current Behavior

if err := header.ValidateBasic(); err != nil {
    // TODO(tzdybal): I think this is could be even a panic, because if this happens, header is FUBAR
    m.logger.Error("header validation error", "error", err)
}

Expected Behavior

The code should panic when a newly produced header fails validation, as this indicates a critical error in the block production process that requires immediate attention and cannot be safely recovered from.

Impact

• Continuing with an invalid header could lead to:
  • Stalling the node (due to headers not being removed from the channel used for communication with go-header)
  • Potential security vulnerabilities
  • P2P sync issues

Proposed Solution

Replace the error logging with a panic when header validation fails:

if err := header.ValidateBasic(); err != nil {
    panic(fmt.Errorf("critical: newly produced header failed validation: %w", err))
}

Additional Context

• This validation happens after block creation but before saving
• The header is freshly produced by the node itself, not received from peers
• A validation failure at this stage indicates a bug in the block production logic (missing fields, invalid signatures, etc)
• Panicking would help catch these issues early in development and testing