This commit modifies the error return type for errors during script
validation to use the RuleError so they are consistent with the rest of
the errors. This also helps the calling code differentiate blocks
rejected due to script parsing and validation errors as opposed to
internal issues such as inability to read from the disk.
To accomplish this, two new two new RuleErrors, ErrScriptMalformed and
ErrScriptValidation, have been added.
Also, the errors for script parsing issues and script validation errors
have been improved to include both transaction hashes and indexes involved
in the validation effort. Previously script parsing issues had almost no
additional information as to which transaction input/outputs the failing
script came from.
This commit changes the RuleError type to a struct which consists of an
error code and human-readable description.
From a usage perspective, existing code should not break since type
asserting an error to a RuleError still works in the same manner. The
difference is the caller can now take that type asserted RuleError and
access the .ErrorCode field on it to programmatically identify the
specific rule that was violated.
ok @jrick
