Continue even if script returns errors

/bin/sh stops execution upon finding a nonzero exit code,
which means that startkde will not continue if a script in
.config/plasma-workspace/env/ produces an error.

This small fix will execute a no-op in such a case,
so that errors will not affect startkde's progress,
while still being visible in .xsession-errors.

REVIEW: 125323
BUG: 352491