Allows the text reader to fail cleanly when the user attempts to recover after catching IonException, but recovery is not possible.

[tgregg]

Issue #, if available:

FasterXML/jackson-dataformats-binary#471

Description of changes:

Sometimes errors conveyed via IonException are recoverable, and sometimes they are not. In cases where these exceptions are not recoverable but the user tries anyway (by calling another method on the reader), the reader should fail cleanly by throwing another IonException. Before this fix, the added test failed with AssertionError here because a save point had been started on a value that was later found to be invalid. The proposed fix clears the current save point if the current value is found to be malformed. This allows the reader to throw another IonException when the invalid character is encountered again during a subsequent request from the user. Note: the diff looks large, but it's just due to the added nesting level. The only change is the addition of the try/catch.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (3c1b6b1) 67.23% compared to head (c067930) 67.26%.
Report is 4 commits behind head on master.

❗ Current head c067930 differs from pull request most recent head 7e411b5. Consider uploading reports for the commit 7e411b5 to get more accurate results

Files	Patch %	Lines
...in/java/com/amazon/ion/impl/IonReaderTextRawX.java	71.05%	6 Missing and 5 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #709      +/-   ##
============================================
+ Coverage     67.23%   67.26%   +0.02%     
- Complexity     5484     5488       +4     
============================================
  Files           159      159              
  Lines         23025    23030       +5     
  Branches       4126     4126              
============================================
+ Hits          15481    15490       +9     
+ Misses         6262     6261       -1     
+ Partials       1282     1279       -3     

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[jobarr-amzn]

The diff is quite small if whitespace is hidden: https://github.com/amazon-ion/ion-java/pull/709/files?diff=unified&w=1 .