Do not crash when no parent window was found
Do not crash when no parent window was found

As this turns out to be more easily triggered than originallay
anticipated:
>> test: make gob! [flags: [no-title no-border on-top]]
>> view/as-is/no-wait test
REBOL Host Failure:
Parent window can't be found

However, the result might not be as expected.

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