</p>

<h2 id="Errors">Errors</h2>

<p>
The predeclared type <code>error</code> is defined as
</p>

<pre>
type error interface {
	Error() string
}
</pre>

<p>
It is the conventional interface for representing an error condition,
with the nil value representing no error.
For instance, a function to read data from a file might be defined:

pkg debug/elf, type Symbol struct, Version string
pkg encoding/csv, method (*ParseError) Unwrap() error
pkg encoding/json, method (*MarshalerError) Unwrap() error
pkg errors, func As(error, interface{}) bool
pkg errors, func Is(error, error) bool
pkg errors, func Unwrap(error) error
pkg go/constant, func Make(interface{}) Value
pkg go/constant, func Val(Value) interface{}
pkg go/token, func IsExported(string) bool

pkg io/fs, var ErrClosed error
pkg io/fs, var ErrExist error
pkg io/fs, var ErrInvalid error
pkg io/fs, var ErrNotExist error
pkg io/fs, var ErrPermission error
pkg io/fs, var SkipDir error
pkg log, func Default() *Logger
pkg net, var ErrClosed error
pkg net/http, func FS(fs.FS) FileSystem
pkg net/http, type Transport struct, GetProxyConnectHeader func(context.Context, *url.URL, string) (Header, error)