[backport#17444] wallet: Avoid showing GUI popups on RPC errors (take 2)

Summary:
wallet: Avoid showing GUI popups on RPC errors (take 2) (MarcoFalke)

Pull request description:

Commit 8b0d82bb428de9e7f1da7c61574e7a8376a62d43 claims "This commit does not change behavior." However, it re-introduced the bug I tried to fix in #17070

Backport of Core PR17444

Test Plan:

ninja check check-functional

Reviewers: #bitcoin_abc, jasonbcox

Reviewed By: #bitcoin_abc, jasonbcox

Differential Revision: https://reviews.bitcoinabc.org/D7684