> In general, there is no way in R7RS-small to create an object which
> satisfies a specific error predicate.  The objects thrown by `error`
> are generic errors, but they are not a supertype of all error objects;
> indeed, the only reliable supertype of {all error objects} is {all objects}.
Yes, however R7RS even says an object satisfies `read-error?` or
`file-error?` may or may not satisfy `error-object?`. So it would be
nice to have this sentence so that if an implementation supports R6RS
or SRFI-35 (which I believe `condition-type?` can be `error-object?`)
may extend their the empty list queue error on top of their condition
system.

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_/_/
Takashi Kato
E-mail: xxxxxx@ymail.com