naqtn
The string in question is this: 35520
Local player is null!
And the context is:
Local player is a networking term to refer to the player that is using the client. A player being a general gaming and networking term in this case specifically meaning an instance of a user in a networked instance.
This is shown in popups when the local player is null and the user is trying to set a profile picture or user icon. Do not translate it the same as you would translate user to avoid confusion.
This string is inappropriate as a UI message for average users and should be rephrased. This violates good practices in many ways when composing UI messages for good UX.
In general, well-composed UI messages
  1. Give users a solution
  2. Get rid of technical terms
  3. Avoid (snip) exclamation marks in the message
(citing from https://medium.com/thinking-design/how-to-write-design-user-friendly-error-messages-87d0207bb902 )
For each point, I think:
  1. This string doesn't help the users at all with what they should do next when they are "trying to set a profile picture or user icon."
  2. Local player
    and
    null
    are technical terms; the average user can't understand what the message means. A string that users cannot understand is entirely meaningless in UI.
  3. The exclamation mark expresses an unexpected condition for the programmer, not for users. Since the string is for the programmer, it is inappropriate as a UI message.
I suggest, for example, "Failed to change the image due to error. Try again later." to give users a solution.
If
Local player is null
has some value to investigate for the dev team, adding it at the end like "(Detail: Local player is null)" might work. You may also be able to leave that detail cause part out of the localization to minimize the translators' effort (by pushing out with the
{0}
placeholder).