[LyX/master] Fix crash due to invalid pos

[Juergen Spitzmueller]

commit 8226453684ee2a41d9ef569af130f5fced9d8433
Author: Juergen Spitzmueller <sp...@lyx.org>
Date:   Tue May 20 11:14:13 2014 +0200

    Fix crash due to invalid pos

diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index 4f8f14a..1f47ca7 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -872,7 +872,7 @@ void TeXOnePar(Buffer const & buf,
        default:
                // we don't need it for the last paragraph!!!
                // or if the last thing is an environment separator
-               if (nextpar && !par.isEnvSeparator(par.size() - 1))
+               if (nextpar && par.size() > 0 && !par.isEnvSeparator(par.size() 
- 1))
                        pending_newline = true;
        }
 
@@ -1018,7 +1018,7 @@ void TeXOnePar(Buffer const & buf,
        // we don't need a newline for the last paragraph!!!
        // Note from JMarc: we will re-add a \n explicitly in
        // TeXEnvironment, because it is needed in this case
-       if (nextpar && !par.isEnvSeparator(par.size() - 1)) {
+       if (nextpar && par.size() > 0 && !par.isEnvSeparator(par.size() - 1)) {
                // Make sure to start a new line
                os << breakln;
                Layout const & next_layout = nextpar->layout();