Fix subscribing to null sessionToken

[dplewis]

Closes: #1055

This PR just forces sessionToken null to be undefined when intializing the client.

If anybody knows how a sessionToken can be null instead of a string, '', or undefined, let me know.

[codecov]

Codecov Report

Merging #1058 into master will not change coverage.
The diff coverage is 100%.

@@           Coverage Diff           @@
##           master    #1058   +/-   ##
=======================================
  Coverage   92.18%   92.18%           
=======================================
  Files          54       54           
  Lines        5146     5146           
  Branches     1148     1149    +1     
=======================================
  Hits         4744     4744           
  Misses        402      402

Impacted Files	Coverage Δ
src/LiveQueryClient.js	87.76% <100%> (ø)	⬆️

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[dplewis]

@acinader How does this look?

[acinader]

hm. does the test case fail without the this.sessionToken = sessionToken || undefined;

if i've got it right, your code is changing null to undefined. null errors, undefined doesn't?

it's kidna an odd construct cause the first time i read it i saw, if undefined, make undefined, but now i see its if falsey, make undefined.

[dplewis]

The test does fail without this fix. undefined doesn’t error.

I can’t think of a case where sessionToken could be null.