add forgotten '...' in logger.Fatal

[vladvelici]

I've noticed that log.Fatal(msg, err) messages are actually missing the err in the logs.

For this code

log := unalogger.New("yo")
log.Fatal("hello", fmt.Errorf("world"))

I expected to see something like this in the output (which is what we get with this patch)

17:31:34.004229 CRITICAL yo hello error: world

but instead I found this

17:28:27.413387 CRITICAL yo hello _: [error map[]]

I noticed it works just fine for log.Error, and the only difference was the missing "...", causing the arguments slice to be interpreted as the first argument.

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