Program: 54758
Project: 54758
Buggy source:
private static Handler prettyPage(final ClassLoader loader,final SourceLocator locator,final int maxStackSize,final Logger log){
  String css=readString(loader,"String_Node_Str");
  String clipboard=readString(loader,"String_Node_Str");
  String js=readString(loader,"String_Node_Str");
  String zepto=readString(loader,"String_Node_Str");
  ClasspathLoader cpathloader=new ClasspathLoader();
  cpathloader.setPrefix("String_Node_Str");
  cpathloader.setSuffix("String_Node_Str");
  PebbleEngine engine=new PebbleEngine.Builder().loader(cpathloader).templateCache(CacheBuilder.newBuilder().maximumSize(10).build()).build();
  Throwing.Function<String,PebbleTemplate> template=Throwing.<String,PebbleTemplate>throwingFunction(name -> engine.getTemplate(name)).memoized();
  return (req,rsp,err) -> {
    if (req.accepts(MediaType.html).isPresent()) {
      Throwable cause=Optional.ofNullable(err.getCause()).orElse(err);
      List<Throwable> causal=Throwables.getCausalChain(cause);
      Throwable head=causal.get(causal.size() - 1);
      String message=message(head);
      Map<String,Object> envdata=new LinkedHashMap<>();
      envdata.put("String_Node_Str",dump(() -> ImmutableMap.of("String_Node_Str",rsp.status().get())));
      envdata.put("String_Node_Str",dump(() -> {
        Route route=req.route();
        ImmutableMap.Builder<String,Object> map=ImmutableMap.builder();
        return map.put("String_Node_Str",route.method()).put("String_Node_Str",route.path()).put("String_Node_Str",route.vars()).put("String_Node_Str",route.pattern()).put("String_Node_Str",route.name()).put("String_Node_Str",route.attributes()).build();
      }
));
      envdata.put("String_Node_Str",dump(() -> req.params().toMap()));
      envdata.put("String_Node_Str",dump(req::attributes));
      envdata.put("String_Node_Str",dump(req::headers));
      req.ifSession().ifPresent(s -> envdata.put("String_Node_Str",dump(s::attributes)));
      List<Map<String,Object>> frames=causal.stream().filter(it -> it != head).map(it -> frame(loader,locator,it,it.getStackTrace()[0])).collect(Collectors.toList());
      frames.addAll(frames(loader,locator,head));
      frames=frames.subList(0,Math.min(maxStackSize,frames.size()));
      Map<String,Object> context=ImmutableMap.<String,Object>builder().put("String_Node_Str",css).put("String_Node_Str",zepto).put("String_Node_Str",clipboard).put("String_Node_Str",js).put("String_Node_Str",causal).put("String_Node_Str",head.getClass().getName() + "String_Node_Str" + message).put("String_Node_Str",message).put("String_Node_Str",Throwables.getStackTraceAsString(cause)).put("String_Node_Str",frames).put("String_Node_Str",envdata).build();
      Writer writer=new StringWriter();
      template.apply("String_Node_Str").evaluate(writer,context);
      log.error("String_Node_Str",req.method(),req.path(),req.route().print(6),err);
      rsp.type(MediaType.html).send(writer.toString());
    }
  }
;
}

Fixed version (ground truth):
private static Handler prettyPage(final ClassLoader loader,final SourceLocator locator,final int maxStackSize,final Logger log){
  String css=readString(loader,"String_Node_Str");
  String clipboard=readString(loader,"String_Node_Str");
  String js=readString(loader,"String_Node_Str");
  String zepto=readString(loader,"String_Node_Str");
  ClasspathLoader cpathloader=new ClasspathLoader();
  cpathloader.setPrefix("String_Node_Str");
  cpathloader.setSuffix("String_Node_Str");
  PebbleEngine engine=new PebbleEngine.Builder().loader(cpathloader).templateCache(CacheBuilder.newBuilder().maximumSize(10).build()).build();
  Throwing.Function<String,PebbleTemplate> template=Throwing.throwingFunction(engine::getTemplate).memoized();
  return (req,rsp,err) -> {
    if (req.accepts(MediaType.html).isPresent()) {
      Throwable cause=Optional.ofNullable(err.getCause()).orElse(err);
      List<Throwable> causal=Throwables.getCausalChain(cause);
      Throwable head=causal.get(causal.size() - 1);
      String message=message(head);
      Map<String,Object> envdata=new LinkedHashMap<>();
      envdata.put("String_Node_Str",dump(() -> ImmutableMap.of("String_Node_Str",rsp.status().get())));
      envdata.put("String_Node_Str",dump(() -> {
        Route route=req.route();
        ImmutableMap.Builder<String,Object> map=ImmutableMap.builder();
        return map.put("String_Node_Str",route.method()).put("String_Node_Str",route.path()).put("String_Node_Str",route.vars()).put("String_Node_Str",route.pattern()).put("String_Node_Str",route.name()).put("String_Node_Str",route.attributes()).build();
      }
));
      envdata.put("String_Node_Str",dump(() -> req.params().toMap()));
      envdata.put("String_Node_Str",dump(req::attributes));
      envdata.put("String_Node_Str",dump(req::headers));
      req.ifSession().ifPresent(s -> envdata.put("String_Node_Str",dump(s::attributes)));
      List<Map<String,Object>> frames=causal.stream().filter(it -> it != head).map(it -> frame(loader,locator,it,it.getStackTrace()[0])).collect(Collectors.toList());
      frames.addAll(frames(loader,locator,head));
      frames=frames.subList(0,Math.min(maxStackSize,frames.size()));
      Map<String,Object> context=ImmutableMap.<String,Object>builder().put("String_Node_Str",css).put("String_Node_Str",zepto).put("String_Node_Str",clipboard).put("String_Node_Str",js).put("String_Node_Str",causal).put("String_Node_Str",head.getClass().getName() + "String_Node_Str" + message).put("String_Node_Str",message).put("String_Node_Str",Throwables.getStackTraceAsString(cause)).put("String_Node_Str",frames).put("String_Node_Str",envdata).build();
      Writer writer=new StringWriter();
      template.apply("String_Node_Str").evaluate(writer,context);
      log.error("String_Node_Str",req.method(),req.path(),req.route().print(6),err);
      rsp.type(MediaType.html).send(writer.toString());
    }
  }
;
}