Can we have On Error Resume Next option to resume in errors?

You have 3 options:

1 --- use exists()
implement more intervening checks with exists() to assure, that is visible on the screen, what you expect to go on with your workflow, either with appropriate max waiting times or waiting loops. This makes your script more robust.

2 --- catch FindFailed
a similar approach, but you move the recovery to the exception handling. Since this is relatively complex, I generally prefer option 1, because it is better integrated into the workflow.

3 --- use the interactive FindFailed options
When the script stops, you get a prompt and can arrange the affected app, so the script might go on repeating or skipping the failed action. Currently it is not possible, to show additional text, that might help the user.
see: http://sikuli.org/docx/region.html#exception-findfailed
Be aware, that this option is a Region option: it has to be set for every region independently.

Thanks RaiMan,

While i use exists(), is there any way i can display a user friendly error like "Browser not open" etc... and then exit program?

Secondly,

Is there any way to resume in errors instead of hanging up?

Thanks

--- While i use exists(), is there any way i can display a user friendly error like "Browser not open" etc... and then exit program?

if not exists(img):
    popup("error message")
    exit(1)

--- Is there any way to resume in errors instead of hanging up?
use the above option 3 (SKIP or RETRY)