message: Fix a type error
diff: @@ -115,15 +115,16 @@ export class Manager {
  }
  findAllDependentFiles() {
  + let prevWatcherClosed = false
  if (this.fileWatcher !== undefined && pathNotWatched(this.fileWatcher, this.rootFile)) {
  // We have an instantiated fileWatcher, but the rootFile is not being watched.
  // => the user has changed the root. Clean up the old watcher so we reform it.
  this.extension.logger.addLogMessage(`Root file changed -> cleaning up old file watcher.`)
  this.fileWatcher.close()
  - this.fileWatcher = undefined
  + prevWatcherClosed = true
  }
  - if (this.fileWatcher === undefined) {
  + if (prevWatcherClosed || this.fileWatcher === undefined) {
  this.extension.logger.addLogMessage(`Instatiating new file watcher for ${this.rootFile}`)
  this.fileWatcher = chokidar.watch(this.rootFile)
  this.fileWatcher.on('change', path => {
  