There is a problem with your gallery's 'config.xml' file.
There is a control character (not a regular text character) in the middle of the image title for the 16th image in your gallery ("14 - Potion fb.jpg").
If you view your gallery's 'config.xml' file directly in a browser (https://maelys-tremblay.fr/Galerie/inkt … config.xml), the browser will let you know at what point in the file the error occurs (Line Number 167, Column 41).
In Firefox, when I view your gallery's 'config.xml' file, I see the following (if there were no errors, you'd see the code for the whole file).
The control character is a STX (start of text) character but I do not know how it got in there (maybe you copied and pasted the image title from another source?).
In any case, if you delete the image title for image #16 ("14 - Potion fb.jpg") and enter it again (just type it in this time rather than copying and pasting from the original source), then all should be well.
Please let me know how you get on and if I can be of any further assistance.