refactor: common error interface for elcontracts chainReader

[maximopalopoli]

Do not merge

What Changed?

The idea is to create a common interface to all SDK errors. The structure of this common interface is currently:

type Error struct {
	code        int
	message     string
	description string
	cause       error
}

The code is associated with the message, which could change in the future, such that one of both must be kept and the other must be replaced or transformed.

One use example could be the following:

func (r *ChainReader) IsOperatorRegistered(
	ctx context.Context,
	operator types.Operator,
) (bool, error) {
	if r.delegationManager == nil {
		wrappedError := CreateErrorForMissingContract("DelegationManager")
		return false, wrappedError
	}
...
}

func CreateErrorForMissingContract(contractName string) Error {
	errDescription := fmt.Sprintf("%s contract not provided", contractName)
	return Error{1, "Missing needed contract", errDescription, nil}
}

So, in this use example the error message would be the following:

"Missing needed contract(1) - DelegationManager contract not provided"

Reviewer Checklist

• Code is well-documented
• Code adheres to Go naming conventions
• Code deprecates any old functionality before removing it

[damiramirez]

What do you think about creating a type of "enum" for the errors codes? Maybe it would be more expressive?

I think that we can do something like this:

type ErrorCode int

const (
    ErrCodeBindingError ErrorCode = 0
    ErrCodeMissingContract
    ErrCodeNestedError
)

Do you think this is a good option? If not, we can use the current implementation.

[maximopalopoli]

Yes, I thought about leaving a comment or something in the code that clarifies what type of error each ID is equivalent to, but I would prefer not to do so until I clearly define what error each one is equivalent to (it could change)

[damiramirez]

Do we need this?

[maximopalopoli]

No, I left it just in case but could not find any use. Removed in 6978c58

[damiramirez]

LGTM! Just left some comments

[MegaRedHand]

Let's rename these functions to MissingContractError, BindingError, XError, etc.

[maximopalopoli]

Done in Rename custom error builders and its occurrences

[MegaRedHand]

Let's introduce another function for this kind of "Other errors", although we could probably find a category to move it to.

[maximopalopoli]

Yes, I thought about renaming some of them to "logic errors", but preferred to keep "others" for now.

[MegaRedHand]

Let's use the full syntax here:

Suggested change

	0,
	"Binding error",
	errDescription,
	errorCause,
	code: 0,
	message: "Binding error",
	description: errDescription,
	cause: errorCause,

[MegaRedHand]

Let's make it "DelegationManager.delegationApprover" following the solidity casing.

[MegaRedHand]

We can use ErrorContains here.

[MegaRedHand]

We should expose this as a variable.