Properly type check values for APPEND to file ports
Properly type check values for APPEND to file ports

Currently, APPEND on a file port! is just a shortcut for WRITE/append.
However, APPEND has a less restrictive type spec than WRITE/append.
WRITE only accepts [binary! string! block!], whereas APPEND accepts any
type.

Currently, calling APPEND on a file port with a value not also supported
by WRITE has a high chance of crashing the interpreter. For example,
consider CureCode issue 1894:

    >> p: open/new %pokus.txt
    >> append p #"x"  ;; Crashes the interpreter.

This commit fixes the crash by adding additional type checks for APPEND
on file ports:

    >> p: open/new %pokus.txt
    >> append p #"x"
    ** Script error: invalid argument: #"x"
    ** Where: append
    ** Near: append p #"x"

This fixes CureCode issue 1894.

hostilefork/rebol,kealist/ren-c,hostilefork/rebol,codebybrett/ren-c,draegtun/ren-c,mbk/ren-c,giuliolunati/ren-c,giuliolunati/ren-c,draegtun/ren-c,kealist/ren-c,codebybrett/ren-c,codebybrett/ren-c,hostilefork/rebol,kealist/ren-c,codebybrett/ren-c,mbk/ren-c,kealist/ren-c,mbk/ren-c,rgchris/ren-c,draegtun/ren-c,giuliolunati/ren-c,rgchris/ren-c,giuliolunati/ren-c,codebybrett/ren-c,giuliolunati/ren-c,hostilefork/rebol,draegtun/ren-c,mbk/ren-c,hostilefork/rebol,kealist/ren-c,rgchris/ren-c,hostilefork/rebol,codebybrett/ren-c,draegtun/ren-c,rgchris/ren-c,rgchris/ren-c,kealist/ren-c,draegtun/ren-c