fix: handle TOML parsing errors in config reader

marimo/_utils/config/config.py

@@ -36,7 +36,7 @@ def read_toml(self, cls: Type[T], *, fallback: T) -> T:
             with open(self.filepath, "r") as file:
                 data = tomlkit.parse(file.read())
                 return parse_raw(data, cls, allow_unknown_keys=True)
-        except FileNotFoundError:
+        except (FileNotFoundError, tomlkit.exceptions.TOMLKitError):
             return fallback
 
     def write_toml(self, data: Any) -> None:

tests/_utils/config/test_config_reader.py

@@ -0,0 +1,40 @@
+# Copyright 2024 Marimo. All rights reserved.
+from __future__ import annotations
+
+import os
+from dataclasses import dataclass
+from tempfile import NamedTemporaryFile
+
+from marimo._utils.config.config import ConfigReader
+
+
+@dataclass
+class TestConfig:
+    value: str
+
+
+def test_read_toml_invalid_syntax() -> None:
+    with NamedTemporaryFile(mode="w", suffix=".toml", delete=False) as f:
+        # Write invalid TOML content (missing value after comma)
+        f.write("key = 'value',")
+        f.flush()
+
+        reader = ConfigReader(f.name)
+        fallback = TestConfig(value="fallback")
+        result = reader.read_toml(TestConfig, fallback=fallback)
+        assert result == fallback
+
+    os.unlink(f.name)
+
+
+def test_read_toml_valid() -> None:
+    with NamedTemporaryFile(mode="w", suffix=".toml", delete=False) as f:
+        f.write('value = "test"')
+        f.flush()
+
+        reader = ConfigReader(f.name)
+        fallback = TestConfig(value="fallback")
+        result = reader.read_toml(TestConfig, fallback=fallback)
+        assert result == TestConfig(value="test")
+
+    os.unlink(f.name)