1 files changed, 27 insertions, 0 deletions
diff --git a/tools/cru-py/cru/_error.py b/tools/cru-py/cru/_error.py
new file mode 100644
index 0000000..0d2bf79
--- /dev/null
+++ b/tools/cru-py/cru/_error.py
@@ -0,0 +1,27 @@
+from typing import NoReturn
+
+
+class CruException(Exception):
+    """Base exception class of all exceptions in cru."""
+
+
+class CruUnreachableError(CruException):
+    """Raised when a code path is unreachable."""
+
+
+def cru_unreachable() -> NoReturn:
+    raise CruUnreachableError()
+
+
+class CruInternalError(CruException):
+    """Raised when an internal logic error occurs."""
+
+
+class CruUserFriendlyException(CruException):
+    def __init__(self, message: str, user_message: str, *args, **kwargs) -> None:
+        super().__init__(message, *args, **kwargs)
+        self._user_message = user_message
+
+    @property
+    def user_message(self) -> str:
+        return self._user_message