refactor: replace fmt.Errorf with MessageTooBigError

Author: DanielleMaywood

read.go

@@ -17,6 +17,14 @@ import (
 	"github.com/coder/websocket/internal/util"
 )
 
+type MessageTooBigError struct {
+	Limit int64
+}
+
+func (e MessageTooBigError) Error() string {
+	return fmt.Sprintf("read limited at %v bytes", e.Limit)
+}
+
 // Reader reads from the connection until there is a WebSocket
 // data message to be read. It will handle ping, pong and close frames as appropriate.
 //
@@ -520,7 +528,7 @@ func (lr *limitReader) Read(p []byte) (int, error) {
 	}
 
 	if lr.n == 0 {
-		err := fmt.Errorf("read limited at %v bytes", lr.limit.Load())
+		err := MessageTooBigError{Limit: lr.limit.Load()}
 		lr.c.writeError(StatusMessageTooBig, err)
 		return 0, err
 	}