Improve UX for permission errors in storage

This commit:
* Improves the error message displayed when the dark storage server does not have access to the storage path.
* Makes the dark storage server return a response with status code 401 - unauthorized when the `get_ensemble_record` endpoint fails due to `PermissionError`.
* Makes the failed message in `LegacyEnsemble._evaluate_inner` omit stacktrace when it failed due to PermissionError, making it shorter and more consise.

src/ert/dark_storage/endpoints/records.py

@@ -66,7 +66,12 @@ async def get_record_observations(
                 "text/csv": {},
                 "application/x-parquet": {},
             }
-        }
+        },
+        status.HTTP_401_UNAUTHORIZED: {
+            "content": {
+                "application/json": {"example": {"error": "Unauthorized access"}}
+            },
+        },
     },
 )
 async def get_ensemble_record(
@@ -77,7 +82,10 @@ async def get_ensemble_record(
     accept: Annotated[Union[str, None], Header()] = None,
 ) -> Any:
     name = unquote(name)
-    dataframe = data_for_key(storage.get_ensemble(ensemble_id), name)
+    try:
+        dataframe = data_for_key(storage.get_ensemble(ensemble_id), name)
+    except PermissionError as e:
+        raise HTTPException(status_code=401, detail=str(e)) from e
     media_type = accept if accept is not None else "text/csv"
     if media_type == "application/x-parquet":
         dataframe.columns = [str(s) for s in dataframe.columns]

src/ert/ensemble_evaluator/_ensemble.py

@@ -303,7 +303,10 @@ async def _evaluate_inner(  # pylint: disable=too-many-branches
 
             self._scheduler.add_dispatch_information_to_jobs_file()
             result = await self._scheduler.execute(min_required_realizations)
-
+        except PermissionError as error:
+            logger.exception((f"Unexpected exception in ensemble: \n {error!s}"))
+            await event_unary_send(event_creator(Id.ENSEMBLE_FAILED))
+            return
         except Exception as exc:
             logger.exception(
                 (

src/ert/gui/tools/plot/plot_api.py

@@ -89,6 +89,8 @@ def get_all_ensembles(self) -> List[EnsembleObject]:
 
     @staticmethod
     def _check_response(response: httpx._models.Response) -> None:
+        if response.status_code == httpx.codes.UNAUTHORIZED:
+            raise httpx.RequestError(message=f"{response.text}")
         if response.status_code != httpx.codes.OK:
             raise httpx.RequestError(
                 f" Please report this error and try restarting the application."

src/ert/gui/tools/plot/plottery/plots/histogram.py

@@ -121,7 +121,7 @@ def plotHistogram(
         if use_log_scale:
             axes[ensemble.name].set_xscale("log")
 
-        if not data[ensemble.name].empty:
+        if ensemble.name in data and not data[ensemble.name].empty:
             if categorical:
                 config.addLegendItem(
                     ensemble.name,