git signed commit fails if gpg key is locked

[timtmok]

          Is there any documentation for how to use the new commit signing feature?

When pressing the Commit button with "Sign commit" checked, I expected a prompt to ask me to unlock my key, but instead I get an error:

error: gpg failed to sign the data
fatal: failed to write commit object

It works as expected if I first unlock my key from the terminal.

Originally posted by @jeffkeller-einc in https://github.com/rstudio/rstudio/issues/1865#issuecomment-1750682628

[timtmok]

A prompt to enter the password or a message that it needs to be unlocked from the terminal would help the user understand what is going on.

[sharon-wang]

cc @jthomasmock To add content in user guide

[ronblum]

I created issue #13781 to track the documentation separately.