add error handling to endpoint

pkgs/clan-cli/clan_cli/webui/routers/flake.py

@@ -1,4 +1,5 @@
 import json
+from json.decoder import JSONDecodeError
 from pathlib import Path
 
 from fastapi import APIRouter, HTTPException
@@ -15,9 +16,21 @@ router = APIRouter()
 async def inspect_flake_attrs(url: str) -> FlakeAttrResponse:
     cmd = nix_flake_show(url)
     stdout = await run_cmd(cmd)
-    data = json.loads(stdout)
-    nixos_configs = data["nixosConfigurations"]
+
+    data: dict[str,dict] = {}
+    try:
+        data = json.loads(stdout)
+    except JSONDecodeError:
+        raise HTTPException(status_code=422, detail=f"Could not load flake.")
+    
+
+    nixos_configs = data.get("nixosConfigurations",{})
     flake_attrs = list(nixos_configs.keys())
+
+    if not flake_attrs:
+        raise HTTPException(status_code=422, detail="No entry or no attribute: nixosConfigurations")
+
+
     return FlakeAttrResponse(flake_attrs=flake_attrs)