What version of Go are you using (go version)?

$ go version
go version go1.12.1 darwin/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

N/A

What did you do?

package main

import ("errors";"fmt")

func main() {
	var s [1]int
	s[0], err1 := 1, errors.New("some error")  // error: non-name s[0] on left side of :=
	fmt.Printf("%v\n", err1)
	
	var err2 error
	s[0], err2 = 1, errors.New("some error") // all good	
	fmt.Printf("%v %v\n", s[0], err2)
	
	var i int
	i, err3 := 1, errors.New("some other error") // all good	
	fmt.Printf("%v %v", i, err3)
}

You can try it out here: https://play.golang.org/p/OIy7TJWnSkF

What did you see?

• if I change the operation to multiple assignment (pre-initialise err2), everything works as expected.
• if instead of s[i] (dereferencing an array) I use a single value (var i int), the mixed assignment/short declaration works as advertised.

What did you expect to see?

• at best I would expect Go to compile the program (not an unreasonable expectation IMO; given that multiple initialisation works, I don't see why short var declaration wouldn't).
• at the very least I would expect a better compiler error.