altoslib: Check for empty gps height series
authorKeith Packard <keithp@keithp.com>
Sun, 28 May 2017 21:42:30 +0000 (14:42 -0700)
committerKeith Packard <keithp@keithp.com>
Sun, 28 May 2017 21:42:30 +0000 (14:42 -0700)
When the gps height series is present but empty, there won't be a max value.

Signed-off-by: Keith Packard <keithp@keithp.com>

No differences found