fix: memory leak in InsideDollar

[jodavies]

Fixes the leak discovered in #648

[coveralls]

Pull Request Test Coverage Report for Build 15676169172

Details

• 7 of 8 (87.5%) changed or added relevant lines in 1 file are covered.
• 2 unchanged lines in 1 file lost coverage.
• Overall coverage increased (+0.02%) to 50.401%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
sources/dollar.c	7	8	87.5%

Files with Coverage Reduction	New Missed Lines	%
sources/threads.c	2	77.56%

Totals
Change from base Build 15649636236:	0.02%
Covered Lines:	41811
Relevant Lines:	82956

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💛 - Coveralls

[jodavies]

Updated: I added a test, this leak is specifically when you work inside a dollar variable that is zero.