diff --git a/src/incremental/_hatch.py b/src/incremental/_hatch.py
index 39ddcb7..b7e5325 100644
--- a/src/incremental/_hatch.py
+++ b/src/incremental/_hatch.py
@@ -20,9 +20,7 @@ class IncrementalVersionSource(VersionSourceInterface):
 
     def get_version_data(self) -> _VersionData:  # type: ignore[override]
         path = os.path.join(self.root, "./pyproject.toml")
-        # If the Hatch plugin is running at all we've already opted in.
         config = _load_pyproject_toml(path)
-        assert config is not None, "Failed to read {}".format(path)
         return {"version": _existing_version(config.version_path).public()}
 
     def set_version(self, version: str, version_data: Dict[Any, Any]) -> None:
diff --git a/src/incremental/tests/test_pyproject.py b/src/incremental/tests/test_pyproject.py
index d0f1c0b..0d1f021 100644
--- a/src/incremental/tests/test_pyproject.py
+++ b/src/incremental/tests/test_pyproject.py
@@ -52,9 +52,10 @@ def test_fileNotFound(self):
 
     def test_brokenToml(self):
         """
-        Syntactially invalid TOML is ignored unless there's an opt-in.
+        Syntactially invalid TOML produces an exception. The specific
+        exception varies by the underlying TOML library.
         """
-        toml = '[project]\nname = "abc'  # truncated
+        toml = '[project]\nname = "abc'  # Truncated string.
         self.assertRaises(Exception, self._loadToml, toml)
 
     def test_nameMissing(self):
@@ -72,8 +73,7 @@ def test_nameMissing(self):
 
     def test_nameInvalidOptIn(self):
         """
-        Once opted in, `TypeError` is raised when the project name
-        isn't a string.
+        `TypeError` is raised when the project name isn't a string.
         """
         for toml in [
             "[project]\nname = false\n",
@@ -85,9 +85,8 @@ def test_nameInvalidOptIn(self):
 
     def test_toolIncrementalInvalid(self):
         """
-        When ``[tool]`` or ``[tool.incremental]`` isn't a table the
-        ``pyproject.toml`` it's an error if opted-in, otherwise the
-        file is ignored.
+        `ValueError` is raised when the ``[tool]`` or ``[tool.incremental]``
+        isn't a table.
         """
         for toml in [
             "tool = false\n",