Fix potential out of bounds read.
Review Request #128153 - Created June 11, 2016 and submitted
|Martin Tobias Holmedahl Sandsmark|
The check was only done when not memory mapped, so there was a potential out of bounds read. In addition the check only printed an error, and didn't return and went ahead with the erronous read.
Tested running with the unlimited scrollback and various amounts of printing and scrolling to try to trigger both the mmaped and unmmaped cases.