Fix OpLoadEnv disassemble

Author: antonmedv

vm/program.go

@@ -97,6 +97,9 @@ func (program *Program) Disassemble() string {
 		case OpLoadFunc:
 			argument("OpLoadFunc")
 
+		case OpLoadEnv:
+			code("OpLoadEnv")
+
 		case OpFetch:
 			code("OpFetch")
 
@@ -270,7 +273,7 @@ func (program *Program) Disassemble() string {
 			code("OpEnd")
 
 		default:
-			_, _ = fmt.Fprintf(w, "%v\t%#x\n", ip, op)
+			_, _ = fmt.Fprintf(w, "%v\t%#x (unknown)\n", ip, op)
 		}
 	}
 	_ = w.Flush()

vm/program_test.go

@@ -15,7 +15,7 @@ func TestProgram_Disassemble(t *testing.T) {
 			Arguments: []int{1},
 		}
 		d := program.Disassemble()
-		if strings.Contains(d, "\t0x") {
+		if strings.Contains(d, "(unknown)") {
 			t.Errorf("cannot disassemble all opcodes")
 		}
 	}

vm/vm.go

@@ -125,6 +125,7 @@ func (vm *VM) Run(program *Program, env interface{}) (_ interface{}, err error)
 
 		case OpLoadEnv:
 			vm.push(env)
+
 		case OpMethod:
 			a := vm.pop()
 			vm.push(runtime.FetchMethod(a, program.Constants[arg].(*runtime.Method)))