Not compatible with PHP 7.1

I’m getting this error when checking compatibility with PHP 7.1

FILE: /home/demadmin/public_html/wp-content/plugins/wp-scss/scssphp/src/SourceMap/Base64VLQEncoder.php
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FOUND 3 ERRORS AFFECTING 1 LINE
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179 | ERROR | Bitwise shifts by negative number will throw an ArithmeticError in PHP 7.0
179 | ERROR | Bitwise shifts by negative number will throw an ArithmeticError in PHP 7.0
179 | ERROR | Bitwise shifts by negative number will throw an ArithmeticError in PHP 7.0
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