x/tools/gopls: "extract method" creates invalid code when extracting free "continue" statement

[adonovan]

When extracting statements from the body of a loop that include continue, but not the enclosing loop, gopls seems not to notice the implications of the continue statement, and this generates invalid code. Extracting:

func f(cond bool) {
	for range "abc" {
|		if cond {
|			continue
|		}
|		println(0)
	}
}

becomes:

func f(cond bool) {
	for range "abc" {
		newFunction1(cond)
	}
}

func newFunction1(cond bool) {
	if cond {
		continue // error: continue not in loop
	}
	println(0)
}

This is a pity since the extract logic seems to go to great trouble to deal with return continuations.