[LyX/master] Improve debug message

[Jean-Marc Lasgouttes]

commit 46ca4e9aa62208c413a5662017804a2a3cde6697
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Fri Nov 20 22:43:45 2015 +0100

    Improve debug message

diff --git a/src/CoordCache.cpp b/src/CoordCache.cpp
index 53f1d0a..62c970a 100644
--- a/src/CoordCache.cpp
+++ b/src/CoordCache.cpp
@@ -41,12 +41,17 @@ void CoordCache::clear()
 
 void CoordCache::dump() const
 {
+       if (getInsets().data_.empty()) {
+               LYXERR0("InsetCache is empty.");
+               return;
+       }
+
        LYXERR0("InsetCache contains:");
        CoordCache::Insets::cache_type::const_iterator it =
                getInsets().data_.begin();
        for (; it != getInsets().data_.end(); ++it) {
                // Warning: it is not guaranteed that inset is a valid pointer
-               // (therefore it has type 'void *') (see bug #7376).    
+               // (therefore it has type 'void *') (see bug #7376).
                void const * inset = it->first;
                Point const p = it->second.pos;
                LYXERR0("Inset " << inset << " has point " << p.x_ << "," << 
p.y_);