SDK / exoplayer

Throw a ParserException instead of a NullPointerException if the sample table (stbl) is missing a required sample description (stsd).

As per the javadoc for AtomParsers.parseTrack, ParserException should be "thrown if the trak atom can't be parsed."

PiperOrigin-RevId: 499522748
(cherry picked from commit bbe78b10)