fix: splash hangs forever on "Loading Cargo Data" when a cargo download fails

src/cargomanager.py

@@ -413,7 +413,13 @@ def get_cargo_data(
                         if cargo_data is not None:
                             store_json(cargo_data, cargo_file)
                             return cargo_data
-                # TODO what happens when both backups fail?
+                # Download failed and no usable backup exists (typical on a
+                # fresh install when the wiki/GitHub cache is unreachable).
+                # Raise so the caller surfaces a real error instead of silently
+                # returning None — which would crash with TypeError further up.
+                raise RuntimeError(
+                    f"Could not obtain cargo table '{filename}': download "
+                    f"failed and no backup is available.")
             else:
                 return self.get_cargo_data(filename, url, ignore_cache_age=True)
         else:

src/downloader.py

@@ -2,7 +2,7 @@
 from os import getenv as os__getenv
 from pathlib import Path
 from requests import Session
-from requests.exceptions import Timeout
+from requests.exceptions import RequestException
 from time import time
 from threading import Thread
 from typing import Callable
@@ -93,7 +93,7 @@ def fetch_json(self, url: str) -> dict | list | None:
                 response.encoding = 'utf-8'
                 return json__loads(compensate_json(response.text))
             return None
-        except (Timeout, JSONDecodeError):
+        except (RequestException, JSONDecodeError, ValueError):
             return None
 
     def download_cargo_table(self, url: str, file_name: str) -> dict | list | None:

src/widgets.py

@@ -296,6 +296,7 @@ class Thread(QThread):
     """
     result: Signal = Signal(object)
     done: Signal = Signal()
+    error: Signal = Signal(object)
 
     def __init__(self, target: Callable, args: tuple = (), kwargs: dict[str] = {}):
         super().__init__()
@@ -318,9 +319,19 @@ def set_args(self, new_args: tuple) -> bool:
     def run(self):
         """
         This function will be executed in a separate thread.
+
+        `done` is always emitted, even if the target raises, so callers waiting
+        on it (e.g. the splash screen) are never left hanging. Exceptions are
+        re-emitted via `error` so they can be logged or surfaced in the UI.
         """
-        self.result.emit(self._target(*self._args, **self._kwargs))
-        self.done.emit()
+        try:
+            self.result.emit(self._target(*self._args, **self._kwargs))
+        except BaseException as exc:
+            import traceback
+            traceback.print_exc()
+            self.error.emit(exc)
+        finally:
+            self.done.emit()
 
 
 class ShipButton(QLabel):