message: Raise a warning message when viewer cannot find PDF file
diff: @@ -161,6 +161,7 @@ export class Viewer {
  const pdfFile = this.extension.manager.tex2pdf(sourceFile, respectOutDir)
  if (!fs.existsSync(pdfFile)) {
  this.extension.logger.addLogMessage(`Cannot find PDF file ${pdfFile}`)
  + this.extension.logger.displayStatus('check', 'statusBar.foreground', `Cannot view file PDF file. File not found: ${pdfFile}`, 'warning')
  return
  }
  if (this.extension.server.address === undefined) {
  