Double Header: fix max_rows & empty chunk bugs

[dougbrn]

Addresses #207 and #208.

No unit tests added as this is repr code, but verified that the reproducible examples in the issues now work.

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 98.29%. Comparing base (a416b6b) to head (88e5a4e).
Report is 179 commits behind head on main.

Files with missing lines	Patch %	Lines
src/nested_pandas/nestedframe/core.py	57.14%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #209      +/-   ##
==========================================
- Coverage   98.43%   98.29%   -0.15%     
==========================================
  Files          13       13              
  Lines        1152     1232      +80     
==========================================
+ Hits         1134     1211      +77     
- Misses         18       21       +3     

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[github-actions]

Before [495b047]	After [224f3b0]	Ratio	Benchmark (Parameter)
31.5±1ms	41.1±10ms	~1.31	benchmarks.ReassignHalfOfNestedSeries.time_run
33.0±8ms	26.3±0.3ms	~0.80	benchmarks.AssignSingleDfToNestedSeries.time_run
10.8±0.1ms	10.9±0.1ms	1.01	benchmarks.NestedFrameQuery.time_run
270M	269M	1.00	benchmarks.AssignSingleDfToNestedSeries.peakmem_run
92M	92.1M	1.00	benchmarks.NestedFrameAddNested.peakmem_run
9.73±0.1ms	9.70±0.1ms	1.00	benchmarks.NestedFrameAddNested.time_run
96.5M	96.8M	1.00	benchmarks.NestedFrameQuery.peakmem_run
95.8M	95.9M	1.00	benchmarks.NestedFrameReduce.peakmem_run
289M	289M	1.00	benchmarks.ReassignHalfOfNestedSeries.peakmem_run
1.27±0.01ms	1.23±0.01ms	0.97	benchmarks.NestedFrameReduce.time_run

Click here to view all benchmarks.