Chnged to use GetOp instead & added error + checking

vm/errors.go

@@ -0,0 +1,51 @@
+package vm
+
+import (
+	"fmt"
+	"math/big"
+)
+
+type OutOfGasError struct {
+	req, has *big.Int
+}
+
+func OOG(req, has *big.Int) OutOfGasError {
+	return OutOfGasError{req, has}
+}
+
+func (self OutOfGasError) Error() string {
+	return fmt.Sprintf("out of gas! require %v, have %v", self.req, self.has)
+}
+
+func IsOOGErr(err error) bool {
+	_, ok := err.(OutOfGasError)
+	return ok
+}
+
+type StackError struct {
+	req, has int
+}
+
+func StackErr(req, has int) StackError {
+	return StackError{req, has}
+}
+
+func (self StackError) Error() string {
+	return fmt.Sprintf("stack error! require %v, have %v", self.req, self.has)
+}
+
+func IsStack(err error) bool {
+	_, ok := err.(StackError)
+	return ok
+}
+
+type DepthError struct{}
+
+func (self DepthError) Error() string {
+	return fmt.Sprintf("Max call depth exceeded (%d)", MaxCallDepth)
+}
+
+func IsDepthErr(err error) bool {
+	_, ok := err.(DepthError)
+	return ok
+}