This input causes the unreachable analyzer to report a diagnostic
about the var decl statement. Since the computed End pos of
ast.StructType is beyond EOF, validation of SuggestedFixes fails.
This used to trigger an assertion in gopls' analysis driver.

See golang/go#71659 (and also #71812).

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a
func _() { return; var x struct{
