refactor(api): rename dify_graph to graphon (#34095)

api/graphon/nodes/code/exc.py

@@ -0,0 +1,16 @@
+class CodeNodeError(ValueError):
+    """Base class for code node errors."""
+
+    pass
+
+
+class OutputValidationError(CodeNodeError):
+    """Raised when there is an output validation error."""
+
+    pass
+
+
+class DepthLimitError(CodeNodeError):
+    """Raised when the depth limit is reached."""
+
+    pass