Is it necessary to restart Spacemacs to install packages?

[Kazark]

After SPC f e U, a message is printed advising:

--> performing backup of package(s) to update...
--> preparing update of package yaml-mode... [46/46]
--> 46 package(s) to be updated.

Restart Emacs to install the updated packages. (SPC q r)

However I found accidentally that doing SPC f e d (open .spacemacs) SPC f e R installed the packages, though with an error:

Restart Emacs to install the updated packages. (SPC q r)
Error in dotspacemacs/user-init: Wrong type argument: symbolp, 22
Found 44 new package(s) to install...
--> installing package: yaml-mode@yaml... [44/44]

(Technically I also added evil-better-jumper layer before SPC f e R.)

What kind of state am I in? Do I need a restart?

[lebensterben]

Error in dotspacemacs/user-init: Wrong type argument: symbolp, 22

Similar bug should have been reported and it happened to me also.
Probably error code 213 but I'm not sure.
Anyway 22 is not a printable character, but a control character. And this is a bug. I've tried to debug this but failed.

[pataquets]

If you want Spacemacs to do it, I'm afraid it is.
However, if you want to just test some random package quickly, you can use Emacs' package-install command an try it right away. Later, if you decide to keep it, don't forget to add it to Spacemacs' init.el or it will be deleted (docs)