restructure package. Change label extraction strategy.

errors.go

@@ -0,0 +1,33 @@
+// Package errors defines standard error types used throughout the roots-ws library.
+package envelope
+
+import (
+	"errors"
+)
+
+var (
+	// Data Structure Errors
+
+	// ErrInvalidJSON indicates that a byte sequence could not be parsed as valid JSON.
+	// This is typically returned when unmarshaling fails during envelope processing.
+	ErrInvalidJSON = errors.New("invalid JSON")
+
+	// ErrMissingField indicates that a required field is absent from a data structure.
+	// This is returned when validating that all mandatory components are present.
+	ErrMissingField = errors.New("missing required field")
+
+	// ErrWrongFieldType indicates that a field's type does not match the expected type.
+	// This is returned when unmarshaling a specific value fails due to type mismatch.
+	ErrWrongFieldType = errors.New("wrong field type")
+
+	// Envelope Errors
+
+	// ErrInvalidEnvelope indicates that a message does not conform to the Nostr envelope structure.
+	// This typically occurs when an array has incorrect number of elements for its message type.
+	ErrInvalidEnvelope = errors.New("invalid envelope format")
+
+	// ErrWrongEnvelopeLabel indicates that an envelope's label does not match the expected type.
+	// This is returned when attempting to parse an envelope using a Find function that
+	// expects a different label than what was provided.
+	ErrWrongEnvelopeLabel = errors.New("wrong envelope label")
+)