getTelemetryFileSize() {
    return !!this.fileSize ? this.fileSize : !!this.text ? this.text.length : !!this.svc ? this.svc.getSnapshot().getLength() : this.getSnapshot().getLength();
  }
For telemetry purposes, we would like to be able to report the size of the file.
However, we do not want telemetry to require extra file I/O so we report a size
that may be stale (e.g. may not reflect change made on disk since the last reload).
NB: Will read from disk if the file contents have never been loaded because
telemetry falsely indicating size 0 would be counter-productive.