feat: error for when there is more source code than parsed

pkg/saccharine/token/token.go

@@ -45,3 +45,24 @@ func NewSlash(index int) *Token {
 func NewAtom(name string, index int) *Token {
 	return &Token{Type: Atom, Index: index, Value: name}
 }
+
+func Name(typ Type) string {
+	switch typ {
+	case OpenParen:
+		return "("
+	case CloseParen:
+		return ")"
+	case Slash:
+		return "\\"
+	case Dot:
+		return "."
+	case Atom:
+		return "ATOM"
+	default:
+		return "?"
+	}
+}
+
+func (t Token) Name() string {
+	return Name(t.Type)
+}