core/local/chokidar: Guard against missing `old`
core/local/chokidar: Guard against missing `old`

  Events and changes don't always have an `old` attribute so methods
  checking for its own attributes' values should guard against its
  absence.

cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop,cozy-labs/cozy-desktop