api/schema: don't crash on eval error

pkgs/clan-cli/clan_cli/config/schema.py

@@ -10,6 +10,7 @@ from clan_cli.dirs import (
     nixpkgs_source,
     specific_flake_dir,
 )
+from clan_cli.errors import ClanError
 from clan_cli.nix import nix_eval
 
 from ..types import FlakeName
@@ -75,5 +76,5 @@ def machine_schema(
         )
     if proc.returncode != 0:
         print(proc.stderr, file=sys.stderr)
-        raise Exception(f"Failed to read schema:\n{proc.stderr}")
+        raise ClanError(f"Failed to read schema:\n{proc.stderr}")
     return json.loads(proc.stdout)

pkgs/clan-cli/tests/test_machines_api.py

@@ -22,6 +22,21 @@ def test_machines(api: TestClient, test_flake: FlakeForTest) -> None:
     assert response.json() == {"machines": [{"name": "test", "status": "unknown"}]}
 
 
+@pytest.mark.with_core
+def test_schema_errors(api: TestClient, test_flake_with_core: FlakeForTest) -> None:
+    # make sure that eval errors do not raise an internal server error
+    response = api.put(
+        f"/api/{test_flake_with_core.name}/schema",
+        json={"imports": ["some-inavlid-import"]},
+    )
+    assert response.status_code == 422
+    # expect error to contain "error: string 'some-inavlid-import' doesn't represent an absolute path"
+    assert (
+        "error: string 'some-inavlid-import' doesn't represent an absolute path"
+        in response.json()["detail"][0]["msg"]
+    )
+
+
 @pytest.mark.with_core
 def test_configure_machine(api: TestClient, test_flake_with_core: FlakeForTest) -> None:
     # ensure error 404 if machine does not exist when accessing the config