Error report: Crash with Search Button on iOS App ver. 4.5.10

Hi, I just tried iOS App ver. 4..5.10 with my iPhone iOS 12.2.

I find that crash happens with searching when I put any EN word(s) in searching box and tap Search button.

exception: I also find it works when searching with one JP letter, that would respond "too short" message. (crash can be seen with two or more letters)

I hope it would be solved.

Thanks in anyhow I can read lots of e-books