[SAVE REQUIRED, TODO: add warning] field 'image' > default image popup fails when field not yet saved

[setup]
FC 3.0.8
J 3.4.4

[reproduce]
create new field. (Do not Save or Apply Field.)
select field type "Image or Gallery (image + details)". (Do not Save or Apply Field.)
go to 'FIELD TYPE specific configuration' > 'Thumbnails' > 'Thumbnail Creation' > 'Default Image'
press button 'Select'.
*** Here popup fails, previoulsy entered field config is gone.
Above does work, hoever, when field was saved before.

Hello

yes you need save,

the JS needed but the Joomla form element 'meida' is currently not loaded

- i ll open an issue to examine trying to load JS,
e.g. we load JS for bootstrap tooltips

the JS of other Joomla form element too, that are used or will be used in the future may require save (aka form reload before they work)
possibly solutions would be
- either force form save and form reload
- or better add a warning