Move exception in public space

lib/exceptions.dart

@@ -0,0 +1,22 @@
+// Copyright (c) 2020
+// Author: Hugo Pointcheval
+
+class KeyException implements Exception {
+  String message;
+  KeyException(this.message);
+}
+
+class EncryptionException implements Exception {
+  String message;
+  EncryptionException(this.message);
+}
+
+class DecryptionException implements Exception {
+  String message;
+  DecryptionException(this.message);
+}
+
+class NotImplementedException implements Exception {
+  String message;
+  NotImplementedException(this.message);
+}

lib/src/exceptions.dart

@@ -1,27 +0,0 @@
-// Copyright (c) 2020
-// Author: Hugo Pointcheval
-
-class KeyException implements Exception {
-  String error;
-  KeyException(this.error);
-}
-
-class EncryptionException implements Exception {
-  String error;
-  EncryptionException(this.error);
-}
-
-class DecryptionException implements Exception {
-  String error;
-  DecryptionException(this.error);
-}
-
-class PlatformException implements Exception {
-  String error;
-  PlatformException(this.error);
-}
-
-class NotImplementedException implements Exception {
-  String error;
-  NotImplementedException(this.error);
-}