Regression test for golang/go#79399: panic in fromAssignStmt when an
assignment has fewer LHS variables than RHS expressions (LHS < RHS).

When an assignment like "x := Iface(&T{}), Iface2(&R{})" has 1 LHS variable
but 2 RHS expressions, iterating over enclosing nodes for the second RHS
expression (Iface2(&R{})) yields ParentEdgeIndex()=1, which is out of bounds
for Lhs (len=1), causing a panic in assign.Lhs[idx].

-- issue79399.go --
package p

// Regression test for golang/go#79399.

type Writer interface {
	Write([]byte) (int, error)
}

type Reader interface {
	Read([]byte) (int, error)
}

type T struct{}
type R struct{}

// Normal fromAssignStmt case: variable declared as interface, assigned a
// concrete type that doesn't implement it.
func _() {
	var x Writer
	x = &T{} //@quickfix(re"&T{}", re"missing method", stub)
	_ = x
}

// Regression test for golang/go#79399: panic when LHS < RHS.
func _() {
	x := Writer(&T{}), Reader(&R{}) //@quickfixerr(re"&T{}", re"missing method", re"found 0"),quickfixerr(re"&R{}", re"missing method", re"found 0")
	_ = x
}
-- @stub/issue79399.go --
@@ -14 +14,6 @@
+
+// Write implements [Writer].
+func (t *T) Write([]byte) (int, error) {
+	panic("unimplemented")
+}
+
