go/types: panic in error reporting for invalid use of "init" [1.17 only] #48082
Description
The fix in CL 324732 on the dev.typeparams branch should have been back-ported to 1.17, but was missed.
This can result in a panic in go/types when type checking the following invalid code
package p
import "init"
Please consider this for back-port to the next 1.17 minor release.
CC @griesemer @golang/release