fix: panic in process methods

[gusin13]

Noticed errors in process method

"level":"debug","stakingTxHashHex":"3a0e302b928558ae2830a6f3b8179e8f7762d6681f4a5a377ee184410da4af52","currentState":"VERIFIED","time":"2024-11-14T16:07:05Z","message":"Ignoring EventBTCDelgationUnbondedEarly because current state is not qualified for transition"}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x276936e]

goroutine 1 [running]:
github.com/babylonlabs-io/babylon-staking-indexer/internal/services.(*Service).processBTCDelegationUnbondedEarlyEvent(0xc001348080, {0x38bb690, 0x550ca60}, {{0xc001c81400, 0x34}, {0xc002cdf220, 0x4, 0x4}})
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/internal/services/delegation.go:170 +0x6e
github.com/babylonlabs-io/babylon-staking-indexer/internal/services.(*Service).processEvent(0xc001348080, {0x38bb690, 0x550ca60}, {{0x2f1dcf6, 0x2}, {{0xc001c81400, 0x34}, {0xc002cdf220, 0x4, 0x4}}})
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/internal/services/events.go:70 +0x33b
github.com/babylonlabs-io/babylon-staking-indexer/internal/services.(*Service).processBlocksSequentially(0xc001348080, {0x38bb690, 0x550ca60})
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/internal/services/bootstrap.go:79 +0x54c
github.com/babylonlabs-io/babylon-staking-indexer/internal/services.(*Service).StartBbnBlockProcessor(0xc001348080?, {0x38bb690?, 0x550ca60?})
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/internal/services/bootstrap.go:22 +0x1d
github.com/babylonlabs-io/babylon-staking-indexer/internal/services.(*Service).StartIndexerSync(0xc001348080, {0x38bb690, 0x550ca60})
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/internal/services/service.go:70 +0x10d
main.main()
	/go/src/github.com/babylonlabs-io/babylon-staking-indexer/cmd/babylon-staking-indexer/main.go:76 +0x528