CIF-1244 - CIF Core Component fail gracefully

[LSantha]

Fix exception in webpage and error.log for category list, product, product list, product teaser component when the graphqlclient is not available.

Related Issue

CIF-1244

How Has This Been Tested?

Manually, unit tests.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have signed the Adobe Open Source CLA.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes and the overall coverage did not decrease.
• All unit tests pass on CircleCi.
• I ran all tests locally and they pass.

[codecov]

Codecov Report

Merging #231 into master will increase coverage by 0.19%.
The diff coverage is 73.07%.

@@             Coverage Diff              @@
##             master     #231      +/-   ##
============================================
+ Coverage     59.82%   60.01%   +0.19%     
- Complexity      531      545      +14     
============================================
  Files           147      147              
  Lines          4348     4354       +6     
  Branches        736      740       +4     
============================================
+ Hits           2601     2613      +12     
+ Misses         1659     1656       -3     
+ Partials         88       85       -3     

Flag	Coverage Δ	Complexity Δ
#jest	38.47% <ø> (ø)	0.00 <ø> (ø)
#karma	94.97% <ø> (ø)	0.00 <ø> (ø)
#unittests	85.18% <73.07%> (+0.46%)	545.00 <13.00> (+14.00)

Impacted Files	Coverage Δ	Complexity Δ
...models/v1/relatedproducts/RelatedProductsImpl.java	88.63% <50.00%> (+2.27%)	15.00 <3.00> (+1.00)
...nternal/models/v1/productlist/ProductListImpl.java	79.80% <66.66%> (+1.37%)	38.00 <5.00> (+4.00)
...onents/internal/models/v1/product/ProductImpl.java	84.04% <69.23%> (+0.17%)	37.00 <2.00> (+4.00)
...dels/v1/categorylist/FeaturedCategoryListImpl.java	87.23% <100.00%> (+0.27%)	16.00 <0.00> (+1.00)
...nal/models/v1/productteaser/ProductTeaserImpl.java	76.19% <100.00%> (+11.19%)	18.00 <3.00> (+4.00)

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