Return an error if the JAR file doesn't exist

[andymanning]

As a developer creating a tika service using a pre-downloaded JAR file
I want to know if the jar file cannot be found
So that I can report an error

eg.
server, err := tika.NewServer("./lib/tika-server.jar", "1080")

if tika-server.jar is not found in ./lib then an error should be returned.

The error handling in the Start function doesn't return the error when running in background context

func (s *Server) Start(ctx context.Context) error { if _, err := os.Stat(s.jar); os.IsNotExist(err) { return err }

Please assign this issue to me, I'll fix.

[tbpg]

Go for it. Thank you!