Do not allow zero Geometry capacity

[josephbirkner]

Before the geometry is assigned with a vertex array, a negative array handle denotes the desired initial capacity, +1, because there is always the additional offset point. So there can not (and must never be) an initial capacity of zero.

[github-actions[bot]]

Test Results

  1 files  ±0    1 suites  ±0   11s :stopwatch: -1s 39 tests ±0  39 :heavy_check_mark: ±0  0 :zzz: ±0  0 :x: ±0  40 runs  ±0  40 :heavy_check_mark: ±0  0 :zzz: ±0  0 :x: ±0 

Results for commit 2ad40d14. ± Comparison against base commit d0c2b14b.

[github-actions[bot]]

Package	Line Rate	Branch Rate	Health
include.simfil	55%	37%	➖
include.simfil.model	74%	64%	➖
src	63%	35%	➖
src.model	76%	42%	➖
Summary	65% (2267 / 3492)	37% (1888 / 5126)	➖

Minimum allowed line rate is 50%