Go - error: panic: runtime error: invalid memory address or nil pointer dereference

Then looking at this code:

res, err := client.Do(req)
defer res.Body.Close()

if err != nil {
    return nil, err
}

I'm guessing that err is not nil. You're accessing the .Close() method on res.Body before you check for the err.

The defer only defers the function call. The field and method are accessed immediately.

---

So instead, try checking the error immediately.

res, err := client.Do(req)

if err != nil {
    return nil, err
}
defer res.Body.Close()

 

CONNECT_DB:
    _, err = connPool.Query(ctx, "SELECT * FROM users LIMIT 1;")
    fmt.Println(err)
    if strings.Contains(err.Error(), "failed to connect to") {
        if retryTimes < RETRY_LIMIT {
            retryTimes++
            time.Sleep(RETRY_INTERVAL)
            goto CONNECT_DB
        } else {
            log.Fatal("failed to connect to db:", err)
        }
    }

 

zzh@ZZHPC:/zdata/Github/zimplebank$ go run main.go
<nil>
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x9772d3]

goroutine 1 [running]:
main.init.0()
        /zdata/Github/zimplebank/main.go:42 +0x353
exit status 2

Cause: err is nil, but uses err.Error().

Adding nil check can fix this error.