Fix possible IndexOutOfBoundsException

if chainedExceptionIndex stored into the snapshot is incorrect, it can
lead to an IndexOutOfBoundsException. Protect against it

Author: jpbempel

dd-java-agent/agent-debugger/src/main/java/com/datadog/debugger/exception/AbstractExceptionDebugger.java

@@ -146,6 +146,15 @@ private void processSnapshotsAndSetTags(
     int maxSnapshotSize = Math.min(snapshots.size(), maxCapturedFrames);
     for (int i = 0; i < maxSnapshotSize; i++) {
       Snapshot snapshot = snapshots.get(i);
+      int chainedExceptionIdx = snapshot.getChainedExceptionIdx();
+      if (chainedExceptionIdx >= chainedExceptions.size()) {
+        LOGGER.debug(
+            "Chained exception for snapshot={} is out of bounds: {}/{}",
+            snapshot.getId(),
+            chainedExceptionIdx,
+            chainedExceptions.size());
+        continue;
+      }
       Throwable currentEx = chainedExceptions.get(snapshot.getChainedExceptionIdx());
       int[] mapping = createThrowableMapping(currentEx, t);
       StackTraceElement[] innerTrace = currentEx.getStackTrace();