Cannot evaluate functions (str, regexp, iregexp) with sec parameter if there is no data in the period

Trigger become unknown state when trigger expression has str and nodata function.

{host:itemkey.str(error,300)}=1&{host:itemkey.nodata(300)}#1

str(error,300) returns error if there is no history data in the period. It should return 0 (not found) in that case.