Added tests/warnings when SOS is not online

[cdwdirect]

[codecov-io]

Codecov Report

Merging #140 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #140   +/-   ##
=======================================
  Coverage   75.22%   75.22%           
=======================================
  Files         108      108           
  Lines        7658     7658           
=======================================
  Hits         5761     5761           
  Misses       1897     1897

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[daboehme]

We'll have to adapt the SOS service to the new Channel interface before this can be merged. Shouldn't be anything major, mostly the callback dispatch.