Prevent threaded Dask workers in DistRDF backend

Author: JAGANNATHANJP

bindings/distrdf/python/DistRDF/Backends/Dask/Backend.py

@@ -105,7 +105,10 @@ def __init__(self, daskclient: Optional[Client] = None):
         self.client = (daskclient if daskclient is not None else
                        Client(LocalCluster(n_workers=os.cpu_count(), threads_per_worker=1, processes=True)))
 
-        workers = self.client.scheduler_info()["workers"]
+        workers = self.client.scheduler_info().get("workers", None)
+
+        if workers is None:
+            return
 
         for worker in workers.values():
             threads = worker.get("nthreads", 1)
@@ -114,7 +117,7 @@ def __init__(self, daskclient: Optional[Client] = None):
                 raise RuntimeError(
                     "DistRDF with Dask does not support threaded workers. "
                     "Please use processes=True and threads_per_worker=1."
-               )
+                )
 
     def optimize_npartitions(self) -> int:
         """