Prevent subtitle timeout crash

[cewert]

Comes from roku.com crash log:

text             <uninitialized> 
url              roString refcnt=1 val:"http://192.168.1.30:8096/Videos/fb51ac18-d13f-7e61-7821-3ea889a4d2ed/fb51ac18d13f7e6178213ea88"... 
re               roRegex refcnt=1 
m                roAssociativeArray refcnt=2 count:16 
global           Interface:ifGloba$1 Local Variables: 
   file/line: pkg:/components/captionTask.brs(77) 
#0  Function fetchcaption() As Voi$1 Backtrace: 
Execution timeout (runtime error &h23) in pkg:/components/captionTask.brs(77)

which points to this line after running build-prod on 2.1.4:

text = m.reader.GetToString()

Issues

Ref #1164