Boostport/mjml-go

package mjml

import (
    "fmt"
    "strings"
)

type Error struct {
    Message string `json:"message"`
    Details []struct {
        Line    int    `json:"line"`
        Message string `json:"message"`
        TagName string `json:"tagName"`
    } `json:"details"`
}

func (e Error) Error() string {

    var sb strings.Builder

    sb.WriteString(e.Message)

    numDetails := len(e.Details)

    if numDetails > 0 {
        sb.WriteString(":\n")
    }

    for i, detail := range e.Details {
        sb.WriteString(fmt.Sprintf("- Line %d of (%s) - %s", detail.Line, detail.TagName, detail.Message))

        if i != numDetails-1 {
            sb.WriteString("\n")
        }
    }

    return sb.String()
}