#272 Fix parse error on a block sequence containing a comment within

[fktn-k]

As described in #272, a block sequence which contains a comment unexpectedly crashes the fkYAML deserializer.
So, this PR has fixed the crash with the reported input.

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[coveralls]

coverage: 100.0%. remained the same when pulling f8b1c242e93ad8562b6a91138d978b25c0f13fe3 on bugfix/272_fix_parse_block_sequence_with_comments into d79bfae4b49eac5773e731f29eba69954965fdbd on develop.