Fix get_nvidia_cc to handle cases where cuda.cuGetErrorString gives a None result

scripts/utils.py

@@ -82,13 +82,16 @@ def get_nvidia_cc():
     result = cuda.cuInit(0)
     if result != CUDA_SUCCESS:
         cuda.cuGetErrorString(result, ctypes.byref(error_str))
-        return None, error_str.value.decode()
+        if error_str.value:
+            return None, error_str.value.decode()
+        else:
+            return None, "Unknown error: cuInit returned %d" % result
     result = cuda.cuDeviceGetCount(ctypes.byref(nGpus))
     if result != CUDA_SUCCESS:
         cuda.cuGetErrorString(result, ctypes.byref(error_str))
         return None, error_str.value.decode()
 
-    if(nGpus.value < 1):
+    if nGpus.value < 1:
         return None, "No GPUs detected"
 
     result = cuda.cuDeviceGet(ctypes.byref(device), 0)