An error shown when trying to send invalid data to Language (page size) drop-down menu

Preconditions
1)Firefox Developer tool must be installed
2)User should have "Edit profile permissions"

Steps to reproduce:
1)Sing In
2)Go to user Profile
3)Click edit profile button
4)Select "Converts select elements to text inputs" in "Forms" menu on the developer tool panel
5)Enter any text in language field
6)Press "Save"

Actual result: An error shown when tying to save invalid data to Language drop-down menu
Expected result: After saving the language established for the selected before editing.

Note: Can be reproduce in Page size drop-down menu also