Io.output_of() seems to have broken at some point

I am getting this error on my Luanhost'ed website. I am suspecting the chunked encoding commit. Since the error seems about a missing 'flush' method/field, and that commit seems to have introduced the requirement for it. Stack trace:

Internal Server Error

invalid index 'flush' for java class luan.modules.IoLuan$LuanString$1
	luan:Boot.luan line 90 in function 'new_writer'
	luan:Boot.luan line 113 in function 'text_writer'
	luan:Io.luan line 97 in function 'output_of'
	site:/music.html.luan line 331 in function 'file_link'
	site:/music.html.luan line 598

Also, I want to take the opportunity to thank you for the Luanhost (and Luan), it has been running rather well the past few years.

thanks, fixed