fix(memory): panic when dataset is not paired

[pythonbrad]

Now, we ignore unpaired data during the building of the text_buffer via utils::build_map

[coveralls]

Pull Request Test Coverage Report for Build 8458509250

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

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Details

• 2 of 2 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 98.864%

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Totals
Change from base Build 8425807593:	0.0%
Covered Lines:	1480
Relevant Lines:	1497

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💛 - Coveralls