I wonder: Is this an expected error?:

gpgv putty-64bit-0.74-installer.msi.gpg
gpgv: unknown type of key resource 'trustedkeys.kbx'
gpgv: keyblock resource '/home/.../.gnupg/trustedkeys.kbx': General error
gpgv: no signed data
gpgv: can't hash datafile: No data

In contrast, this worked:
> gpg putty-64bit-0.74-installer.msi.gpg
gpg: WARNING: no command supplied.  Trying to guess what you mean ...
Detached signature.
Please enter name of data file: putty-64bit-0.74-installer.msi
gpg: Signature made Sat 27 Jun 2020 09:01:02 AM CEST
gpg:                using RSA key E27394ACA3F9D9049522E0546289A25F4AE8DA82
gpg: Good signature from "PuTTY Releases <putty@projects.tartarus.org>"
[unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: E273 94AC A3F9 D904 9522  E054 6289 A25F 4AE8 DA82

There is no ~/.gnupg/trustedkeys.kbx, but only a ~/.gnupg/trustdb.gpg here.
If the reason is the missing file, why isn't the error message "gpgv: keyblock
resource '/home/.../.gnupg/trustedkeys.kbx': No such file or directory"?