[BUG] Overwriting existing entries unintenionally

[wellemut]

Describe the bug
Unintentionally users will overwrite existing entries with new ones

To Reproduce**

Steps to reproduce the behavior:

1. Go to https://www.kartevonmorgen.org/m/main?c=52.3672%2C9.7374&z=16.00
2. Click on "Add a new entry"
3. Give in a Title, Adress or fill in at least one field of the entry from
4. Click on an existing Pin
5. You see in the URL that the existing pin is opened. But nothing of the existing pin in the entry form is visible. If the user clicks save, he as overwritten the existing entry!!!!!

Expected behavior**

1. When I open an existing entry, while adding a new one, It should have overwritten everything, that I had put in before. I should see all details of the existing entry.
2. It would be nice, if you get a warning "This will open the existing entry. Do you really want to skip your creation of a new entry?"
3. The new entry should not be opend in the edit form but just shown. The user would have to click "edit" before beeing able to edit it.
4. When the user does not click edit but leaves the entry-detail-view, he should see his entry-form he has entered before.

Screenshots
new entryform

existing entry: