buildstats-diff: show more graceful error messages

I got a following error when I run buildstats-diff against a invalid
buildstats file:
| Traceback (most recent call last):
|   File "/poky/scripts/buildstats-diff", line 548, in <module>
|     sys.exit(main())
|   File "/poky/scripts/buildstats-diff", line 534, in main
|     bs1 = read_buildstats(args.buildstats1, args.multi)
|   File "/poky/scripts/buildstats-diff", line 222, in read_buildstats
|     return read_buildstats_dir(path)
|   File "/poky/scripts/buildstats-diff", line 165, in read_buildstats_dir
|     os.path.join(recipe_dir, task))]
|   File "/poky/scripts/buildstats-diff", line 124, in read_buildstats_file
|     bs_task['elapsed_time'] = end_time - start_time
| UnboundLocalError: local variable 'end_time' referenced before assignment

the root cause is that a task was terminated by me on the terminal,
so the generated buildstats file was invalid, supposing that it would
make the buildstats.sh fail, but the script should give more graceful
error messages.

Signed-off-by: Ming Liu <peter.x.liu@external.atlascopco.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>

0 files changed, 0 insertions, 0 deletions