feat(ext): improve error message for db decryption error (#713)

reana_server/ext.py

@@ -14,8 +14,10 @@
 from flask_limiter.errors import RateLimitExceeded
 from marshmallow.exceptions import ValidationError
 from reana_commons.config import REANA_LOG_FORMAT, REANA_LOG_LEVEL
+from sqlalchemy_utils.types.encrypted.padding import InvalidPaddingError
 from werkzeug.exceptions import UnprocessableEntity
 
+
 from reana_server import config
 
 
@@ -52,6 +54,17 @@ def handle_args_validation_error(error: UnprocessableEntity):
     return jsonify({"message": error_message}), 400
 
 
+def handle_invalid_padding_error(error: InvalidPaddingError):
+    """Error handler for sqlalchemy_utils exception ``InvalidPaddingError``.
+
+    This error handler raises an exception with a more understandable message.
+    """
+    raise InvalidPaddingError(
+        "Error decrypting the database. Did you set the correct secret key? "
+        "If you changed the secret key, did you run the migration command?"
+    ) from error
+
+
 class REANA(object):
     """REANA Invenio app."""
 
@@ -103,3 +116,4 @@ def init_error_handlers(self, app):
         """Initialize custom error handlers."""
         app.register_error_handler(RateLimitExceeded, handle_rate_limit_error)
         app.register_error_handler(UnprocessableEntity, handle_args_validation_error)
+        app.register_error_handler(InvalidPaddingError, handle_invalid_padding_error)