[LyX/master] Add a LATTEST, just in case this ever causes a problem.

[Richard Heck]

commit 7aa6f972da50cab0588a76bc62a8c3216fa97107
Author: Richard Heck <rgh...@lyx.org>
Date:   Sat Jun 11 23:08:54 2016 -0400

    Add a LATTEST, just in case this ever causes a problem.
    
    Fixes coverity #23363.

diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index f4d238f..12e3400 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -4622,6 +4622,11 @@ static depth_type getDepth(DocIterator const & it)
                if (!it[i].inset().inMathed())
                        depth += it[i].paragraph().getDepth() + 1;
        // remove 1 since the outer inset does not count
+       // we should have at least one non-math inset, so
+       // depth should nevery be 0. but maybe it is worth
+       // marking this, just in case.
+       LATTEST(depth > 0);
+       // coverity[INTEGER_OVERFLOW]
        return depth - 1;
 }