[Hotfix] Fix boundscheck for foreach_point_neighbor

[efaulhaber]

This bug has two implications:

1. Bounds are not checked correctly, which might cause unchecked out-of-bounds access.
2. Bounds check fails when points is empty.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.15%. Comparing base (16b5269) to head (e9d660b).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/neighborhood_search.jl	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #95   +/-   ##
=======================================
  Coverage   88.15%   88.15%           
=======================================
  Files          15       15           
  Lines         498      498           
=======================================
  Hits          439      439           
  Misses         59       59           

Flag	Coverage Δ
unit	88.15% <66.66%> (ø)

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