Cannot set properties of undefined (setting 'pdfjsWorker')

[versionsai]

使用pdfh5封装pdf预览的UI组件库时，总是会出现如下报错
pdf.worker.js:3 Uncaught TypeError: Cannot set properties of undefined (setting 'pdfjsWorker')
at eval (pdf.worker.js:3:330)
at Module.eval (pdf.worker.js:3:336)
at eval (pdf.worker.js:4:30)
at ./node_modules/pdfh5/js/pdf.worker.js (chunks.js:1794:1)
at webpack_require (site-desktop.js:80:30)
at eval (pdfh5.js:10:21)
at eval (pdfh5.js:22:3)
at ./node_modules/pdfh5/js/pdfh5.js (chunks.js:1805:1)
at webpack_require (site-desktop.js:80:30)
at eval (PdfPreview.vue?./node_modules/cache-loader/dist/cjs.js??ref--1-0!./node_modules/babel-loader/lib!./node_modules/cache-loader/dist/cjs.js??ref--0-0!./node_modules/vue-loader/lib??vue-loader-options:3:63)