Bug: rightOf/leftOf does not work with trailing newline after/before the pattern

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String.Extra.rightOf "_" "abc_\ndef" should return "\ndef", but returns ""

Here is an example on Ellie:

https://ellie-app.com/kr7KLBVx8xQa1

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Same for leftOf:
String.Extra.leftOf "_" "abc\n_def" returns ""