notifications.php - fix old_status_friendly_name undefined warning

[jerclarke]

• affects notification_status_change()
• Moves the definition of $old_status_friendly_name (as well as $new_status_friendly_name) to above the complex else if block to ensure that it is always defined.
• Fixes a recent change to this code, which moved the definition of $old_status_friendly_name to places where it didn’t effect all of the else if clauses:

071791d#diff-59ee072dc425b09b6d748cb84634734b

• This triggered a PHP Warning: PHP Notice: Undefined variable: old_status_friendly_name because the variable is used right after in all cases.
• This warning also reflected that the string would be missing in many cases.
• I tried to test this with all the possible status transition but might have missed some. Certainly the common ones of new->draft->pending->publish->trash are all working as expected now.

[cojennin]

I'd like to merge this in, but it reintroduces a problem mentioned here.

One way it triggers: If you programmatically call wp_insert_post then the $old_status will be new and get_post_status_object will return null, and you'll get an exception here.

One thing I can think of is adding null check around $old_status_post_obj and $new_status_post_obj and make $old_status_friendly_name and $new_status_friendly_name default to something, maybe an empty string?

Open to suggestions. => New Status doesn't seem that odd if we're missing the old status, but Old Status => might be confusing if we're missing the new status

[mjangda]

Continued in #560