fixes positions.isNotEmpty errors

[coveralls]

Pull Request Test Coverage Report for Build 32

• 2 of 3 (66.67%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.2%) to 48.097%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/transformer_page_view.dart	2	3	66.67%
<!--	Total:	2	3	66.67%	-->

Totals
Change from base Build 30:	-0.2%
Covered Lines:	139
Relevant Lines:	289

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💛 - Coveralls