Parse error: syntax error, unexpected '$theme' (T_VARIABLE) in /......./wp-content/themes/optima/lib/constants.php on line 1

 or perhaps

PHP Parse error: syntax error, unexpected '$theme' (T_VARIABLE) in /..../wp-content/themes/Lightbox/lib/constants.php on line 1

what to do:

Simply re-upload the constants.php file.

why?

When you upload the theme with FTP some of your file such as constans.php are compressed and spaces removed from file. That issue comes from some host. Trey to re-upload files that have errors.

seriously.

Hello all,
This is a rather important topic with a rather simple solution:

1. Add to your build an Execute Shell
   
2.  Set the command to something like:

   if [ -f "$file" ]
   then
       echo "$file found."
   else
       echo "$file not found."
       exit 1
   fi

The important part for the failure is exit 1

If the condition meets it (and for what we care they can always meet it), exit 1 will fail the job.

Remembers that anything that fails (even plugins/syntax errors) will make the job fail.
Don’t fail at failing.