Workaround for pandas-dev/pandas#51397

Author: jrbourbeau

dask/dataframe/utils.py

@@ -631,12 +631,12 @@ def index(x):
     results = get(ddf.dask, ddf.__dask_keys__())
     for i, df in enumerate(results[:-1]):
         if len(df):
-            assert index(df).min() >= ddf.divisions[i]
-            assert index(df).max() < ddf.divisions[i + 1]
+            assert min(index(df)) >= ddf.divisions[i]
+            assert max(index(df)) < ddf.divisions[i + 1]
 
     if len(results[-1]):
-        assert index(results[-1]).min() >= ddf.divisions[-2]
-        assert index(results[-1]).max() <= ddf.divisions[-1]
+        assert min(index(results[-1])) >= ddf.divisions[-2]
+        assert max(index(results[-1])) <= ddf.divisions[-1]
 
 
 def assert_sane_keynames(ddf):