Reason of Infinite loop

[zheng-yongping]

require 'gnuplotrb'
puts GnuplotRB::Plot.new('XXX').to_svg()

It may work like this:

create error handler thread (but not running)
check_errors => ok
check_errors => ok
.
.
.
check_errors => ok
handler thread start...
sleep 0.01 until File.size?(inner_opts[:output]) => loop forever

The error handler thread may start after all check ran, and the exception can not be raise.