Fix: Subscriber handler errors silently swallowed causing potential data loss

[NitinKumar004]

Bug Description

In pkg/gofr/subscriber.go:69-72, when a subscription handler returns an error, it is logged but then discarded by returning nil. This breaks error propagation and can lead to silent data loss.

Root Cause

The error from the handler is intentionally replaced with nil:

err = func(ctx *Context) error {
    defer func() {
        panicRecovery(recover(), ctx.Logger)
    }()
    return handler(ctx)
}(msgCtx)

if err != nil {
    s.container.Logger.Errorf("error in handler for topic %s: %v", topic, err)
    return nil  // BUG: error is swallowed, caller sees success
}

Additionally, on line 77, msg.Commit() is called without checking its return value:

if msg.Committer != nil {
    msg.Commit()  // error return value ignored
}