vm: pretty-print CONVERT and ISTYPE opcodes

pkg/vm/vm.go

@@ -191,6 +191,9 @@ func (v *VM) PrintOps() {
 					v.getOffsetDesc(ctx, catchP), v.getOffsetDesc(ctx, finallyP))
 			case opcode.INITSSLOT:
 				desc = fmt.Sprint(parameter[0])
+			case opcode.CONVERT, opcode.ISTYPE:
+				typ := stackitem.Type(parameter[0])
+				desc = fmt.Sprintf("%s (%x)", typ, parameter[0])
 			case opcode.INITSLOT:
 				desc = fmt.Sprintf("%d local, %d arg", parameter[0], parameter[1])
 			case opcode.SYSCALL:

pkg/vm/vm_test.go

@@ -244,6 +244,8 @@ func TestISTYPE(t *testing.T) {
 func testCONVERT(to stackitem.Type, item, res stackitem.Item) func(t *testing.T) {
 	return func(t *testing.T) {
 		prog := []byte{byte(opcode.CONVERT), byte(to)}
+		v := load(prog)
+		v.PrintOps()
 		runWithArgs(t, prog, res, item)
 	}
 }