Removed @alwaysThrows (dart-lang/yaml_edit#64)

pkgs/yaml_edit/lib/src/errors.dart

diff --git a/pkgs/yaml_edit/lib/src/errors.dart b/pkgs/yaml_edit/lib/src/errors.dart
index 871d40a..1bc961d 100644
--- a/pkgs/yaml_edit/lib/src/errors.dart
+++ b/pkgs/yaml_edit/lib/src/errors.dart
@@ -93,7 +93,6 @@
 
 /// Throws an [AssertionError] with the given [message], and format
 /// [oldYaml] and [newYaml] for information.
-@alwaysThrows
 Error createAssertionError(String message, String oldYaml, String newYaml) {
   return _YamlAssertionError('''
 (package:yaml_edit) $message