report() throws when the tags map fails while being read #37

report(String, Double, Map) can throw into the host program. The README and the class Javadoc both promise that it never does.

Where: src/main/java/software/stephenson/trace/TraceClient.java, report. The method has no try/catch. On the caller's thread it runs withVersion(tags, version), which copies the caller's map with new LinkedHashMap<>(tags), and then json(...), which casts each tag to String in quote(...). Every other path in the client catches IOException | RuntimeException, but this one is outside any such guard.

Two reproductions, both confirmed by a failing test on main (79bfa82):

1. A map that another thread is changing. The copy iterates the map, and a HashMap changed during the iteration throws ConcurrentModificationException. The exception escapes from withVersion, called at TraceClient.java:794:

   java.util.ConcurrentModificationException
     at java.util.LinkedHashMap.<init>
     at software.stephenson.trace.TraceClient.withVersion(TraceClient.java:728)
     at software.stephenson.trace.TraceClient.report(TraceClient.java:794)
   

2. A raw map holding a non-String value. A Bukkit ConfigurationSection.getValues(false) is a Map<String, Object>, so one unchecked cast puts an Integer where json() needs a String:

   java.lang.ClassCastException: class java.lang.Integer cannot be cast to class java.lang.String
   

Why it matters: "Never throws" is one of the properties the client exists to provide. A plugin that reports from a command handler or the server thread gets a stack trace from a usage report, which is exactly the outcome the comment in send() rules out.

Proposed fix: catch RuntimeException around the part of report that reads the caller's map, and drop that report. No log line is written, because this runs on the host's thread and a Handler may do IO there. The two existing drops on that path (a full queue, too many counted events) are silent for the same reason. The wire format, the opt-outs and the bounds are unchanged.

This issue was drafted during a Gardener session (https://github.com/Stephenson-Software/gardener).

drafted by Claude on behalf of Daniel Stephenson