add throwable adapter

Author: wadoon

keyext.api/src/main/java/org/keyproject/key/api/StartServer.java

@@ -146,7 +146,7 @@ public void run() {
     public static void configureJson(GsonBuilder gsonBuilder) {
         gsonBuilder.registerTypeHierarchyAdapter(Object.class, new GenericSerializer());
         gsonBuilder.registerTypeAdapter(File.class, new KeyAdapter.FileTypeAdapter());
-
+        gsonBuilder.registerTypeAdapter(Throwable.class, new KeyAdapter.ThrowableAdapter());
     }
 
     public static Launcher<ClientApi> launch(OutputStream out, InputStream in, KeyApiImpl keyApi) {

keyext.api/src/main/java/org/keyproject/key/api/adapters/KeyAdapter.java

@@ -74,6 +74,17 @@ public JsonElement serialize(Function src, Type typeOfSrc, JsonSerializationCont
         }
     }
 
+    public static class ThrowableAdapter implements JsonSerializer<Throwable> {
+        @Override
+        public JsonElement serialize(Throwable src, Type typeOfSrc, JsonSerializationContext context) {
+            var obj = new JsonObject();
+            obj.add("$class", context.serialize(src.getClass().getSimpleName()));
+            obj.add("message", context.serialize(src.getMessage()));
+            obj.add("cause", context.serialize(src.getCause()));
+            return obj;
+        }
+    }
+
     /*class IdentifiableTypeAdapter implements JsonSerializer<Identifiable>, JsonDeserializer<Identifiable> {
         @Override
         public Identifiable deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException {