Fix potential panic from using host before error check in GetP2PNode

[Copilot]

Addresses review feedback from PR #22: host.ID().String() was called before checking the error returned by newHost(), which would panic if newHost returns nil host on error.

Changes:

• Moved error check immediately after newHost() call
• Only set MyID and P2PNode when err == nil

// Before:
host, err := newHost(ctx, seedInt, ds)
MyID = host.ID().String()  // Panics if host is nil
P2PNode = &host
if err != nil {
    common.Logger.Error("Error while creating P2P node: ", err)
    os.Exit(1)
}

// After:
host, err := newHost(ctx, seedInt, ds)
if err != nil {
    common.Logger.Error("Error while creating P2P node: ", err)
    os.Exit(1)
}
MyID = host.ID().String()
P2PNode = &host

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[Copilot]

Pull request overview

Fixes a potential panic in GetP2PNode by ensuring newHost() errors are handled before dereferencing/using the returned host.

Changes:

• Move the newHost() error check to occur before host.ID() is accessed.
• Only set MyID and P2PNode after confirming err == nil.
• Remove unused indirect Go module dependencies (tidy go.mod/go.sum).

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/internal/protocol/host.go	Prevents nil-host dereference by checking err before accessing host.ID().
src/go.mod	Drops unused indirect dependencies.
src/go.sum	Removes corresponding unused checksums.

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[Copilot]

Consider adding a regression test for this nil-host panic scenario (i.e., when newHost returns (nil, err)). Because GetP2PNode calls os.Exit(1) on error, it’s hard to unit test as-is; a small refactor (e.g., injecting an exit function or returning the error instead of exiting) would make this behavior testable and prevent future regressions.