Fix crashes while reading USFM

[ddaspit]

• properly handle verse 0
• ignore private-use markers
• fixes USFM Parsing Bug: 'Stack Empty' #329

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This change is 

[codecov-commenter]

Codecov Report

❌ Patch coverage is 77.77778% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 72.22%. Comparing base (9638a92) to head (6fc66e4).

Files with missing lines	Patch %	Lines
...chine/Corpora/ScriptureRefUsfmParserHandlerBase.cs	77.77%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #333   +/-   ##
=======================================
  Coverage   72.22%   72.22%           
=======================================
  Files         414      414           
  Lines       35154    35169   +15     
  Branches     4865     4871    +6     
=======================================
+ Hits        25389    25401   +12     
- Misses       8674     8676    +2     
- Partials     1091     1092    +1     

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[Enkidu93]

@Enkidu93 reviewed all commit messages.
Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion

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src/SIL.Machine/Corpora/ScriptureRefUsfmParserHandlerBase.cs line 71 at r2 (raw file):

            if (state.VerseRef.Equals(_curVerseRef) && !_duplicateVerse)
            {
                if (state.VerseRef.VerseNum > 0)

Could we use state.IsVerseText instead?

[ddaspit]

Reviewable status: 0 of 2 files reviewed, 1 unresolved discussion (waiting on @Enkidu93)

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src/SIL.Machine/Corpora/ScriptureRefUsfmParserHandlerBase.cs line 71 at r2 (raw file):

Previously, Enkidu93 (Eli C. Lowry) wrote…

Could we use state.IsVerseText instead?

This issue is specifically about the case where there is a \v 0 marker.

[Enkidu93]

Do you want to put in a PR for the new Machine version or should I?

@Enkidu93 reviewed 1 of 2 files at r2.
Reviewable status: 1 of 2 files reviewed, all discussions resolved

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src/SIL.Machine/Corpora/ScriptureRefUsfmParserHandlerBase.cs line 71 at r2 (raw file):

Previously, ddaspit (Damien Daspit) wrote…

This issue is specifically about the case where there is a \v 0 marker.

OK, I was just thinking since the first thing IsVerseTextchecks is

if (VerseRef.VerseNum == 0)
    return false;
...

we could use it, but maybe that doesn't make as much sense semantically as I thought when I left the comment 😅.

[Enkidu93]

Reviewable status: 1 of 2 files reviewed, all discussions resolved

[ddaspit]

@ddaspit reviewed 1 of 2 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @ddaspit)