Fix search page crash

[cewert]

Prevent crash by validating we were given data from the API. Comes from roku.com crash log:

tmp              <uninitialized> 
item             <uninitialized> 
results          roArray refcnt=1 count:0 
data             Invali$1 m                roAssociativeArray refcnt=3 count:2 
global           Interface:ifGloba$1 query            roString (2.1 was String) refcnt=1 val:"m" 
Local Variables: 
   file/line: pkg:/components/search/SearchTask.brs(13) 
#0  Function search() As Voi$1 file/line: pkg:/source/api/Items.brs(57) 
#1  Function searchmedia(query As String) As Dynami$1 Backtrace: 
'Dot' Operator attempted with invalid BrightScript Component or interface reference. (runtime error &hec) in pkg:/source/api/Items.brs(57)

which points to this line after running build-prod on 2.1.2:

for each item in data.Items

Issues

Ref #1164