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

$ go version
go version go1.17.2 linux/amd64

Does this issue reproduce with the latest release?

Yes

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

$ go env

What did you do?

In this code:

	if a, b := c["foo"]; b {
		fmt.Print(a)
	}

if the variable 'c' is not defined, these errors are reported:

./prog.go:8:10: assignment mismatch: 2 variables but 1 value
./prog.go:8:13: undefined: c

The first error message is misleading and redundant.

https://play.golang.org/p/I0TcR8834tK

What did you expect to see?

Only the second error message (undefined: c).

What did you see instead?

As shown above.