Add Gopherspace crawling!

gopher/errors.go

@@ -0,0 +1,32 @@
+package gopher
+
+import (
+	"gemini-grc/errors"
+)
+
+// GopherError is an error encountered while
+// visiting a Gopher host, and is only for
+// Gopher errors (item type indicator 3).
+type GopherError struct {
+	Err error
+}
+
+func (e *GopherError) Error() string {
+	return e.Err.Error()
+}
+
+func (e *GopherError) Unwrap() error {
+	return e.Err
+}
+
+func NewGopherError(err error) error {
+	return &GopherError{Err: err}
+}
+
+func IsGopherError(err error) bool {
+	if err == nil {
+		return false
+	}
+	var asError *GopherError
+	return errors.As(err, &asError)
+}