fix: runtime error: slice bounds out of range [:-1]

[fracasula]

Description

Fixing the following error:

runtime error: slice bounds out of range [:-1]

Stack trace

BugsnagNotify.func1.1 in /rudder-server/utils/misc/misc.go 1207
(*Once).doSlow in sync/once.go 74
BugsnagNotify.func1 in /rudder-server/utils/misc/misc.go 1196
gopanic in runtime/panic.go 884
goPanicSliceAcap in runtime/panic.go 139
(*batchWebhookTransformerT).batchTransformLoop in /rudder-server/gateway/webhook/webhook.go 330
Setup.func1 in /rudder-server/gateway/webhook/setup.go 67
WithBugsnag.func1 in /rudder-server/utils/misc/misc.go 1217
(*Group).Go.func1 in /go/pkg/mod/golang.org/x/sync@v0.1.0/errgroup/errgroup.go 75

Squadcast incident

Security

• The code changed/added as part of this pull request won't create any security issues with how the software is being used.