Simple copy+paste mistake.

For example, this solves the combination of an explicit format string
'@a@ - @t@' in combination with an MP3 input file that lacks either
artist or title

Found by Coverity

Regression found and reported by zygmund2000 on Github

Fixes a segfault when there is a typo in the <encoder /> setting.

It's no longer relevant.

This reverts commit b0ef65fc.
It's been nicer to read before, and static analysis can ignore this one.

... but keep it in cmdline.c (for now) to "follow the pattern".