The message scan read the first argument of every error variant, so
for EngineError::Disabled it read the command id and missed the reason
the status bar shows. It also read error calls inside comments, such as
a commented-out bad(cmd, "..."), as messages that need catalog rows.
The scan now reads Disabled's second argument and removes // and
/* ... */ comments (nested ones included) before it looks for calls. A
// or /* inside a string or character literal does not start a comment.