Find and use first error message in tracked errors

core/src/main/java/dev/faststats/ErrorHelper.java

@@ -36,7 +36,7 @@ private static JsonObject compileAll(final TrackedError trackedError, @Nullable
                                          @Nullable final Attributes defaultAttributes) {
         final var error = trackedError.error();
         final var report = new JsonObject();
-        final var message = getAnonymizedMessage(error, customPatterns);
+        final var message = anonymize(error.getMessage(), customPatterns);
 
         final var stacktrace = new JsonArray();
         final var header = message != null
@@ -54,7 +54,8 @@ private static JsonObject compileAll(final TrackedError trackedError, @Nullable
         appendCauseChain(error.getCause(), stack, suppress, stacktrace, customPatterns);
 
         report.addProperty("error", error.getClass().getName());
-        if (message != null) report.addProperty("message", message);
+        final var first = anonymize(findFirstMessage(error, null), customPatterns);
+        if (first != null) report.addProperty("message", first);
 
         report.add("stack", stacktrace);
         report.addProperty("handled", trackedError.handled());
@@ -75,7 +76,7 @@ private static void appendCauseChain(@Nullable Throwable cause, final List<Strin
         if (suppress != null) toSuppress.addAll(suppress);
         final var visited = Collections.<Throwable>newSetFromMap(new IdentityHashMap<>());
         while (cause != null && visited.add(cause)) {
-            final var causeMessage = getAnonymizedMessage(cause, customPatterns);
+            final var causeMessage = anonymize(cause.getMessage(), customPatterns);
             final var header = causeMessage != null
                     ? "Caused by: " + cause.getClass().getName() + ": " + causeMessage
                     : "Caused by: " + cause.getClass().getName();
@@ -213,8 +214,16 @@ private static boolean isSameClassLoader(final ClassLoader classLoader, final Cl
         return loader == current;
     }
 
-    private static @Nullable String getAnonymizedMessage(final Throwable error, final List<Map.Entry<Pattern, String>> customPatterns) {
+    private static @Nullable String findFirstMessage(@Nullable final Throwable error, @Nullable Set<Throwable> visited) {
+        if (error == null) return null;
         final var message = error.getMessage();
+        if (message != null) return message;
+        if (visited == null) visited = Collections.newSetFromMap(new IdentityHashMap<>());
+        if (!visited.add(error)) return null;
+        return findFirstMessage(error.getCause(), visited);
+    }
+
+    private static @Nullable String anonymize(@Nullable final String message, final List<Map.Entry<Pattern, String>> customPatterns) {
         if (message == null) return null;
         var truncated = message.length() > MAX_MESSAGE_LENGTH
                 ? message.substring(0, MAX_MESSAGE_LENGTH) + "..."

core/src/test/java/dev/faststats/ErrorTrackerTest.java

@@ -165,6 +165,18 @@ public void nullMessagesAreNotSerializedAsMessageProperty() {
         assertEquals("java.lang.RuntimeException", report.getAsJsonArray("stack").get(0).getAsString());
     }
 
+    @Test
+    public void messageFallsBackToCauseMessage() {
+        final var cause = new IllegalArgumentException("cause message");
+        final var error = new RuntimeException(null, cause);
+
+        tracker.trackError(error);
+
+        final var report = tracker.getFullData().get(0).getAsJsonObject();
+        final var stack = report.getAsJsonArray("stack");
+        assertEquals("cause message", report.get("message").getAsString());
+    }
+
     @Test
     public void nestedCausesAreSerializedInOrder() {
         final var root = new IllegalArgumentException("root secret 172.16.0.9");