[BUG][code-analyzer] SFGE engine fails on for loops with ?? operator

### Have you tried to resolve this issue yourself first?

- [x] I confirm I have gone through the above steps and still have an issue to report

### Bug Description

When running SFGE engine, we see that when ?? is used in a for loop, there is an error
Example snippet

``
for (Account a : aList ?? new List()) {
system.debug('do something');
}
``

I assume this is a bug/issue with underlying AST parser or similar as the ?? operator is relatively new in Apex

### Output / Logs

2025-05-20 00:23:01 ERROR Sfge:159 - Unexpected exception while loading graph
com.salesforce.exception.UnexpectedException: vp[FirstChild->true], vp[BeginLine->29], vp[DefiningType_CaseSafe->EXAMPLECLASS...], vp[LastChild->true], vp[DefiningType->EXAMPLECLASS...], vp[EndLine->29], vp[childIdx->0], vp[BeginColumn->4]
at com.salesforce.graph.build.GremlinUtil.getChildren(GremlinUtil.java:60) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor.visitForEachStatement(MethodPathBuilderVisitor.java:235) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor._visit(MethodPathBuilderVisitor.java:130) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor._visit(MethodPathBuilderVisitor.java:159) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor._visit(MethodPathBuilderVisitor.java:159) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor._visit(MethodPathBuilderVisitor.java:159) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.MethodPathBuilderVisitor.apply(MethodPathBuilderVisitor.java:97) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.AbstractApexVertexBuilder.afterInsert(AbstractApexVertexBuilder.java:169) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.AbstractApexVertexBuilder.buildVertices(AbstractApexVertexBuilder.java:153) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.AbstractApexVertexBuilder.buildVertices(AbstractApexVertexBuilder.java:125) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.AbstractApexVertexBuilder.buildVertices(AbstractApexVertexBuilder.java:35) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.CustomerApexVertexBuilder.build(CustomerApexVertexBuilder.java:21) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.build.Util.buildGraph(Util.java:39) ~[sfge-1.0.0.jar:?]
at com.salesforce.graph.ops.GraphUtil.loadSourceFilesAndFolders(GraphUtil.java:170) ~[sfge-1.0.0.jar:?]
at com.salesforce.Sfge$Dependencies.loadSourceFilesAndFoldersToGraph(Sfge.java:249) ~[sfge-1.0.0.jar:?]
at com.salesforce.Sfge.execute(Sfge.java:153) [sfge-1.0.0.jar:?]
at com.salesforce.Sfge.process(Sfge.java:103) [sfge-1.0.0.jar:?]
at com.salesforce.Sfge.main(Sfge.java:71) [sfge-1.0.0.jar:?]

### Steps To Reproduce

1. Write apex class containing ?? in for loop.
2. run SFGE engine covering aforementioned code
3. refer to logs

### Expected Behavior

?? should be accepted as is valid json.

### Operating System

Windows 11

### Salesforce CLI Version

@salesforce/cli/2.88.6 win32-x64 node-v22.14.0

### Code Analyzer Plugin (code-analyzer) Version

code-analyzer 5.0.0 (>=5.0.0 <6.0.0-0)

### Node Version

v22.14.0

### Java Version

openjdk version "17.0.11" 2024-04-16 LTS OpenJDK Runtime Environment Zulu17.50+19-CA (build 17.0.11+9-LTS) OpenJDK 64-Bit Server VM Zulu17.50+19-CA (build 17.0.11+9-LTS, mixed mode, sharing)

### Python Version

_No response_

### Additional Context (Screenshots, Files, etc)

_No response_

### Workaround

bring ?? outside of for loop, assign variable, then use in for loop.

### Urgency

Low

Reproduziere den Fehler mit dem Apex-for-loop-Beispiel und beginne dann bei MethodPathBuilderVisitor.java, insbesondere bei visitForEachStatement, und verfolge den im Stack Trace angezeigten Aufruf von GremlinUtil.getChildren. Bestätige, dass SFGE die Quelle lädt und ihren Graphen erstellt, ohne UnexpectedException auszulösen, wenn der ??-Operator in der Schleife vorkommt.

Vom Indexierungsmodell aus dem Issue-Text verfasst.