In שופטים ו:כב-כג we find גדעון realizing that he has seen the מלאך ה and apparently worrying that he will die.  ה assures him אל תירא לא תמות.  There seems to be a fairly common idea in תנ”ך that revelation or seeing even a מלאך ה results in death.  We have it hear, we have it with מנוח later in ספר שופטים and we have it at מעמד הר סיני.

It is interesting that this theme continues.  None of these prophets seem to reason that if ה is revealing Himself to them, He probably does not plan to immediately kill them for having “seen” Him.