core: fix error when problem title is not actually string (#704)

packages/hydrooj/src/model/problem.ts

@@ -467,6 +467,7 @@ export class ProblemModel {
         try {
             const problems = await fs.readdir(tmpdir, { withFileTypes: true });
             for (const p of problems) {
+                if (process.env.HYDRO_CLI) logger.info(`Importing problem ${p.name}`);
                 const i = p.name;
                 if (!p.isDirectory()) continue;
                 const files = await fs.readdir(path.join(tmpdir, i));
@@ -491,6 +492,7 @@ export class ProblemModel {
                 }
                 const overrideContent = findOverrideContent(path.join(tmpdir, i));
                 if (pdoc.difficulty && !Number.isSafeInteger(pdoc.difficulty)) delete pdoc.difficulty;
+                if (typeof pdoc.title !== 'string') throw new ValidationError('title', null, 'Invalid title');
                 const docId = await ProblemModel.add(
                     domainId, pid, pdoc.title.trim(), overrideContent || pdoc.content || 'No content',
                     operator || pdoc.owner, pdoc.tag || [], { hidden: pdoc.hidden, difficulty: pdoc.difficulty },