How filter out completion tips that have syntax errors

I'm developing a sentence level java completion plugin. The completion tips are generated by AI models. But some of them contain syntax errors and I want to filter out these tips. 

I've tried some ideas.

Firstly, I concatenate a tip and raw source code, then get a new PSIFile and its VirtualFile. And I use CodeSmellDetector to get error infos. But I always get empty results list. This method just works well for a real VirtualFile（which really exists on disk）but not a LightVirtualFile（which is created from a PSIFile only-in-memory）.

String srcNew = beforeContext + tip + afterContext;
PsiFile newPsiFile = PsiFileFactory.getInstance(project).createFileFromText(psiFile.getName(),
psiFile.getFileType(), srcNew);
VirtualFile virtualFile = psiFile.getViewProvider().getVirtualFile();
List<CodeSmellInfo> codeSmells = CodeSmellDetector.getInstance(project).findCodeSmells(Collections.singletonList(virtualFile));

Then, I wirte srcNew to a temp file and get a VirtualFile, then I delete the temp file.By this method, I can get right results when I type code character one by one. But when I type code fast, I get unexpected results. I think it is caused by multi-thread proplems, but I have no idea about how to solve.

srcNew = srcNew.replace(ori, des);

try {
    BufferedOutputStream writer = new BufferedOutputStream(new FileOutputStream(desPath));
    writer.write(srcNew.getBytes());
    writer.close();
} catch (IOException e) {

}

VirtualFile newFile = LocalFileSystem.getInstance().findFileByIoFile(new File(desPath));

List<CodeSmellInfo> newCodeSmells = CodeSmellDetector.getInstance(project).findCodeSmells(Collections.singletonList(newFile));

try {
    File file = new File(desPath);
    file.delete();
} catch (Exception e) {

}

I prefer the first idea, but I don't know how to check systax errors for a PSIFile only-in-memory. Your suggestions will be greatly appreciated.