check for None first

Author: stevetracvc

bertopic/_bertopic.py

@@ -3180,6 +3180,8 @@ def _reduce_dimensionality(self,
         # Regular fit
         else:
             try:
+                # cuml umap needs y to be a numpy array
+                y = np.array(y) if y is not None else None
                 self.umap_model.fit(embeddings, y=y)
             except TypeError:
                 logger.info("The dimensionality reduction algorithm did not contain the `y` parameter and"