Fix:Error message for invalid task ID

Author: rahul-flex

Diff for: CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 - Compatibility with `xarray>=2025.03`.
+- Error message for invalid task ID.
 
 ## [2.8.1] - 2025-03-20
 

Diff for: tests/test_web/test_webapi.py

@@ -39,6 +39,7 @@
     upload,
 )
 from tidy3d.web.core.environment import Env
+from tidy3d.web.core.exceptions import TaskNotFoundError
 from tidy3d.web.core.types import TaskType
 
 TASK_NAME = "task_name_test"
@@ -722,3 +723,18 @@ def save_sim_to_path(path: str) -> None:
                 "--inspect_sim",
             ]
         )
+
+
+@responses.activate
+def test_load_invalid_task_raises(mock_webapi):
+    """Ensure that load() raises TaskNotFoundError for a non-existent task ID."""
+    fake_id = "INVALID_TASK_ID"
+
+    responses.add(
+        responses.GET,
+        f"{Env.current.web_api_endpoint}/tidy3d/tasks/{fake_id}/detail",
+        json={"error": "Task not found"},
+        status=404,
+    )
+    with pytest.raises(TaskNotFoundError, match="does not exist"):
+        load(fake_id)

Diff for: tidy3d/web/core/exceptions.py

@@ -11,3 +11,9 @@ def __init__(self, message: str = None):
         log = get_logger()
         super().__init__(message)
         log.error(message)
+
+
+class TaskNotFoundError(WebError):
+    """Raised when a requested task ID does not exist on the server."""
+
+    pass

Diff for: tidy3d/web/core/http_util.py

@@ -25,7 +25,7 @@
 )
 from .core_config import get_logger
 from .environment import Env
-from .exceptions import WebError
+from .exceptions import TaskNotFoundError, WebError
 
 REINITIALIZED = False
 
@@ -131,7 +131,9 @@ def wrapper(*args, **kwargs):
 
         if resp.status_code != ResponseCodes.OK.value:
             if resp.status_code == ResponseCodes.NOT_FOUND.value:
-                return None
+                raise TaskNotFoundError(
+                    "The requested task ID does not exist. Please verify your task ID."
+                )
             json_resp = resp.json()
             if "error" in json_resp.keys():
                 raise WebError(json_resp["error"])