testimage.bbclass: add additional dependency

qemu-native-helper has an additional task that needs to be run in order
for testimage to work. This task is usually run by default in a full
build but there are use cases where it might be skipped. This commit
adds the dependency explicitly.

Also, this commit adds a try/catch error message to make it clearer what
you need to do if you try to run testimage before you have built or
downloaded the image artifacts.

[YOCTO #11375]

Signed-off-by: brian avery <brian.avery@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

0 files changed, 0 insertions, 0 deletions