Address debug build errors

[gerashegalov]

Fixes #8564

../tests/copying/gather_struct_tests.cpp:87:48: error: comparison of integer expressions of different signedness: ‘int’ and ‘std::vector<int>::size_type’ {aka ‘long unsigned int’} [-Werror=sign-compare]
   87 |       assert(gather_index >= 0 && gather_index < gather_map.size() || "Gather-index out of range.");
      |                                   ~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~
../tests/copying/gather_struct_tests.cpp:87:32: error: suggest parentheses around ‘&&’ within ‘||’ [-Werror=parentheses]
   87 |       assert(gather_index >= 0 && gather_index < gather_map.size() || "Gather-index out of range.");
      |              ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1plus: all warnings being treated as errors

[codecov]

Codecov Report

Merging #8565 (3c5134e) into branch-21.08 (1de662f) will increase coverage by 0.37%.
The diff coverage is n/a.

@@               Coverage Diff                @@
##           branch-21.08    #8565      +/-   ##
================================================
+ Coverage         82.57%   82.95%   +0.37%     
================================================
  Files               109      109              
  Lines             17817    18173     +356     
================================================
+ Hits              14713    15076     +363     
+ Misses             3104     3097       -7     

Impacted Files	Coverage Δ
python/cudf/cudf/io/feather.py	100.00% <0.00%> (ø)
python/cudf/cudf/comm/serialize.py	0.00% <0.00%> (ø)
python/cudf/cudf/_fuzz_testing/io.py	0.00% <0.00%> (ø)
python/cudf/cudf/utils/applyutils.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/_version.py	0.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_csv.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_orc.py	100.00% <0.00%> (ø)
python/dask_cudf/dask_cudf/io/tests/test_json.py	100.00% <0.00%> (ø)
...ython/dask_cudf/dask_cudf/io/tests/test_parquet.py	100.00% <0.00%> (ø)
python/cudf/cudf/core/column/numerical.py	94.17% <0.00%> (+0.01%)	⬆️
... and 42 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 1de662f...3c5134e. Read the comment docs.

[ttnghia]

This is duplicate of #8554.

[davidwendt]

This is already being fixed in #8554. Recommend closing this PR.