vue.esm.js:1897 Error: Removed API method: PDFDocumentLoadingTask.then, use the `promise` getter instead.

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vue.esm.js:1897 Error: Removed API method: PDFDocumentLoadingTask.then, use the promise getter instead.
at Object.then (pdf.js:1448)
at o.getPdf (index.vue:191)
at o.getInfo (index.vue:166)
at o.init (index.vue:155)
at o.mounted (index.vue:138)
at $e (vue.esm.js:1863)
at nn (vue.esm.js:4228)
at Object.insert (vue.esm.js:3148)
at M (vue.esm.js:6357)
at o.patch (vue.esm.js:6576)

mycode
getPdf () {
var self = this
self.pdfdata = pdf.createLoadingTask(this.pdfUrl)
self.pdfdata.then(pdf => {
self.pdfPages = pdf._pdfInfo.numPages
})
},