test: empty receivers accept incoming funds

[anton-trunov]

Issue

Closes #788.

Checklist

• [x] I have run all the tests locally and no test failure was reported
• [x] I have run the linter, formatter and spellchecker
• [x] I did not do unrelated and/or undiscussed refactorings

[anton-trunov]

that's a copy-paste mistake probably, fixed that

the point is to have small tests for each aspect of the language that needs to be documented