Add nil check for crash

[bbirman]

No description provided.

[bbirman]

There’s a crash reported at this line with reason -[__NSPlaceholderDictionary initWithObjects:forKeys:count:]: attempt to insert nil object from objects[0] but we don’t have app logs or repro steps. It looks like the crash would be because the account is nil so I added a check for that for now but I’d like to dig deeper into why the account is nil if we get any more info

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 62.11%. Comparing base (33923fa) to head (6cf01c0).
Report is 1265 commits behind head on dev.

Additional details and impacted files

@@           Coverage Diff            @@
##           dev    #3799       +/-   ##
========================================
+ Coverage     0   62.11%   +62.11%     
========================================
  Files        0      225      +225     
  Lines        0    21582    +21582     
========================================
+ Hits         0    13406    +13406     
- Misses       0     8176     +8176     

Components	Coverage Δ
Analytics	84.09% <72.09%> (∅)
Common	68.96% <85.90%> (∅)
Core	50.74% <34.55%> (∅)
SmartStore	73.70% <ø> (∅)
MobileSync	87.58% <93.26%> (∅)

Files with missing lines	Coverage Δ
...rceSDKCore/Classes/OAuth/SFOAuthSessionRefresher.m	81.57% <100.00%> (ø)

... and 206 files with indirect coverage changes