Update: it wasn't the ECB blocking gnome-calculator, it was an HTTP library regression breaking the connection to the ECB. Text in [] is incorrect, retained due to RTs etc.
[The ECB have remotely bricked gnome-calculator]
In the latest episode of "Why the 21st Century is impossibly stupid", GNOME calculator contacts the ECB on startup to get currency rates. It just hangs on startup if this fails, the whole calculator not just the currency stuff. [The ECB has blocked GNOME calculator].
To fix this, you can do "dconf write /org/gnome/calculator/refresh-interval 0", whatever tf dconf is, because when I tried it told me dbus-launch is missing, wtf that is, because it doesn't have a package. Turns out it's in "dbus-x11". I dunno why X11, because I use wayland, but I'm past caring at this point. I installed it and it worked.
Now I can calculate how much postage I need to pay for this parcel.
[A bloody OS-shipped desktop calculator, DDoSing a central bank, and blocking on connection failure].
@chiffchaff Yes, this seems to be a lack of testing on the part of GNOME.
@wonka @chiffchaff But, that should have been discovered by another person or team when testing it.
@UlrikNyman That they didn't have test cases for lack of connectivity is again a lack of thinking 
@rugk To do that download on start instead of when the data is needed is just another lack of thinking... As is having a default of "just download without asking if I may".