Catch narrative config errors in store

[willu47]

Closes #342

Unsure as to whether store.py is the best location for these error messages. These types of issues should be caught in configuration validation (see also #343).

[codecov]

Codecov Report

Merging #344 into master will increase coverage by 0.07%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #344      +/-   ##
==========================================
+ Coverage   70.34%   70.41%   +0.07%     
==========================================
  Files          59       59              
  Lines        5119     5125       +6     
  Branches      608      610       +2     
==========================================
+ Hits         3601     3609       +8     
+ Misses       1426     1425       -1     
+ Partials       92       91       -1

Flag	Coverage Δ
#javascript	70.41% <100%> (+0.07%)	⬆️
#python	78.38% <100%> (+0.07%)	⬆️

Impacted Files	Coverage Δ
src/smif/data_layer/store.py	95.76% <100%> (+0.98%)	⬆️

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[tomalrussell]

Throwing errors from the store seems reasonable - for the larger validation story we may want to catch and log them as we scan through the config.