[metrics-bugs] #33433 [Metrics/Onionperf]: Add error handling for older stem versions

[Tor Bug Tracker & Wiki]

#33433: Add error handling for older stem versions
---------------------------------------+--------------------------------
 Reporter:  acute                      |          Owner:  metrics-team
     Type:  defect                     |         Status:  merge_ready
 Priority:  Medium                     |      Milestone:
Component:  Metrics/Onionperf          |        Version:
 Severity:  Normal                     |     Resolution:
 Keywords:  metrics-team-roadmap-2020  |  Actual Points:
Parent ID:  #33321                     |         Points:  0.5
 Reviewer:  karsten                    |        Sponsor:  Sponsor59-must
---------------------------------------+--------------------------------
Changes (by karsten):

 * status:  needs_review => merge_ready
 * reviewer:   => karsten


Comment:

 Patch looks good, will merge together with #30586. Thanks for the analysis
 and for the fix!

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/33433#comment:9>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online