I’m experiencing a similar issue… when an admin post edit page loads, I get this error:
Uncaught TypeError: Cannot read property ‘post_id’ of null
input.js?ver=4.4.5.:991
…then when I try to use the “Add Image” button, I get this error:
Uncaught TypeError: Cannot read property ‘image’ of null
input.js?ver=4.4.5.:2597