Not only does the NAS and the Alexandrian texts contain "tree of life" but also the Majority (Byzantine) text. Every family of Greek manuscripts contains "tree of life", every one. The following is from the Majority text. I bold the two occurances of "book" and the one of "tree".
Rev 22:19καὶ ἐάν τις ἀφέλῃ ἀπὸ τῶν λόγων τοῦ βιβλίου τῆς προφητείας ταύτης, ἀφελεῖ ὁ Θεὸς τὸ μέρος αὐτοῦ ἀπὸ τοῦ ξύλου τῆς ζωῆς καὶ ἐκ τῆς πόλεως τῆς ἁγίας, τῶν γεγραμμένων ἐν τῷ βιβλίῳ τούτῳ.
You can easily see the two uses of "book" in the Greek. Note how different the word translated book looks from the word translated tree. A difficult error in Greek to substitute book with it's two beta's for the word translated tree.
If you have trouble being sure in Greek, see the Majority text translation here
http://www.emtvonline.com/
which reads: (I boldfaced the three words again)
19 And if anyone takes away from the words of the
book of this prophecy, may God take away his part from the
tree of Life, and from the holy city,
and from the things having been written in this
book.
I would also point to his translator's notes,
http://www.emtvonline.com/emtv/revelation/r27tn.htm if you take the time to read them, you will see he considers the Alexandrian manuscripts corrupt and doesn't use them. He uses the Byzantine or Majority text.
So what text does the
Textus Receptus use? There isn't any Greek family to take the text from. That leaves the Latin manuscripts. From the Vulgate we see the original was correct:
Rev 22:19 et si quis deminuerit de verbis libri prophetiae huius auferet Deus partem eius de ligno vitae et de civitate sancta et de his quae scripta sunt in libro isto
Notice how much closer the Latin words are to each other. 5 letters, starts with "l" and note they were handwritten, not neatly typeset. It was probably a common error in Latin manuscripts.
For evidence of that, I will add the Wycliffe translation which was taken from Latin manuscripts.
19 And if ony man do awei of the wordis of the
book of this prophesie, God schal take awei the part of hym fro the
book of lijf, and fro the hooli citee, and fro these thingis that ben writun in this
book.
So you see book in his as well, taken from Latin even though the original Vulgate had it correctly the error occured in his Latin manuscript.
I can understand saying the Byzantine Greek manuscripts are superior to the Alexandrian Greek manuscripts. I do not understand saying that using no Greek manuscript is superior to all Greek manuscripts, and to say the
Textus Receptus is correct in Rev 22:19 makes just that claim.
Marv