Expose exceptions

[robertvazan]

Per #530, but only for three important classes: JsonSerializer, WbGetEntitiesAction, and WbSearchEntitiesAction. There are some spurious exception handlers in dumpfiles/rdf that I have not touched in this pull request.

Calling code within WDTK itself already assumes exceptions. There were no null checks anywhere, so this actually fixes a bug.

This is a breaking change but a very visible one, so there would be no silent failures in apps.

[codecov]

Codecov Report

Merging #539 (dc0e35a) into master (3bc5d8f) will decrease coverage by 0.02%.
The diff coverage is 69.11%.

@@             Coverage Diff              @@
##             master     #539      +/-   ##
============================================
- Coverage     81.04%   81.02%   -0.03%     
+ Complexity     2088     2085       -3     
============================================
  Files           149      149              
  Lines          7306     7293      -13     
  Branches        895      895              
============================================
- Hits           5921     5909      -12     
+ Misses         1116     1115       -1     
  Partials        269      269              

Impacted Files	Coverage Δ	Complexity Δ
...idata/wdtk/datamodel/helpers/JsonDeserializer.java	95.23% <ø> (ø)	6.00 <0.00> (ø)
...idata/wdtk/wikibaseapi/WbSearchEntitiesAction.java	63.63% <63.63%> (-0.26%)	5.00 <5.00> (-1.00)
...wikidata/wdtk/wikibaseapi/WbGetEntitiesAction.java	86.66% <74.19%> (-1.22%)	18.00 <0.00> (-1.00)
...ikidata/wdtk/datamodel/helpers/JsonSerializer.java	68.88% <75.00%> (-2.54%)	11.00 <3.00> (-1.00)

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[wetneb]

Looks like a sensible move, thanks! But the diff seems bigger than it needs to be, at a first glance.

[wetneb]

This seems to be a large piece of code that got reformatted in the process, it's not clear to me what changed there?

[robertvazan]

I am sorry for the large diff. As I have said in #535, there are no coding standards. Most code seems to use tabs. Eclipse doesn't work so well with mixed indentation. I have therefore converted spaces in affected code to tabs. Some code has indentation changes, because try/catch was removed. GitHub fortunately allows you to hide whitespace changes.

I am touching only three classes that are relevant in lexeme I/O. This is all a preparation for #403. Of these classes, JsonSerializer is really essential. The other two are changed for consistency.

I should clarify that this is not really a breaking change as long as WDTK correctly parses entities returned from Wikibase API. New exceptions are thrown only if parsing fails, which would imply a bug in WDTK. All code using Wb*Action classes is already handling IOException, so the new exceptions will be caught when Wikibase data model changes. Only direct JsonSerializer calls require application code changes, but that is only relevant when Wikibase data model changes. If that is a serious enough problem, I can create separate set of methods in JsonSerializer and deprecate the old ones.