[exercises] update display only if we have a viewer, fix #53 (#140)

12 jobs for devel in 13 minutes (queued for 3 seconds)
Status Name Job ID Coverage
  Test
passed doc-coverage #125520

00:12:57

39.0%
failed format #125521
allowed to fail

00:00:59

passed robotpkg-py-tsid-18.04 #125510

00:10:53

passed robotpkg-py-tsid-20.04 #125511

00:00:48

passed robotpkg-py-tsid-buster #125512

00:08:14

passed robotpkg-py-tsid-ferrum #125513

00:01:47

passed robotpkg-py-tsid-stretch #125514

00:12:28

passed robotpkg-tsid-18.04 #125515

00:05:10

passed robotpkg-tsid-20.04 #125516

00:08:55

passed robotpkg-tsid-buster #125517

00:02:29

passed robotpkg-tsid-ferrum #125518

00:05:17

passed robotpkg-tsid-stretch #125519

00:06:44

 
Name Stage Failure
failed
format Test
./demo/demo_quadruped.py:202:35: E231 missing whitespace after ','
./demo/demo_quadruped.py:207:1: W293 blank line contains whitespace
./demo/demo_quadruped.py:208:37: E231 missing whitespace after ','
./demo/demo_quadruped.py:210:31: E231 missing whitespace after ','
./demo/demo_quadruped.py:211:35: E231 missing whitespace after ','
./demo/demo_quadruped.py:212:35: E231 missing whitespace after ','
./demo/demo_quadruped.py:217:1: W293 blank line contains whitespace
Cleaning up file based variables
ERROR: Job failed: exit code 1