Possible Null Pointer Reference

[code-warrior]

Using the command splint main.c +skip-sys-headers -unrecog -compdef to lint this project, Splint says,

main.c:34:11: Index of possibly null pointer screenshot_command_response:
                 screenshot_command_response
  A possibly null pointer is dereferenced.  Value is either the result of a
  function which may return null (in which case, code should check it is not
  null), or a global, parameter or structure field declared with the null
  qualifier. (Use -nullderef to inhibit warning)