Errors

Go has a built-in error type.

• error values are used to indicate abnormal state

error type

type error interface {
    Error() string
}

error is an interface type. An error var represents any value that can describe itself as a string.

• error is predeclared in the universe block
• most commonly used implementation of the error interface is the import "errors" package's unexported errorString type

// errorString is a trivial implementation of error.
type errorString struct {
    s string
}

func (e *errorString) Error() string {
    return e.s
}

source