[LyX/master] Fix assertion

[Juergen Spitzmueller]

commit 54e10dc1ad87245862dd1e6e72c25a2cf0153d3a
Author: Juergen Spitzmueller <spitz at lyx.org>
Date:   Thu Dec 26 12:32:50 2019 +0100

    Fix assertion
---
 src/output_latex.cpp |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/src/output_latex.cpp b/src/output_latex.cpp
index 8a33d51..89974bb 100644
--- a/src/output_latex.cpp
+++ b/src/output_latex.cpp
@@ -745,7 +745,7 @@ void TeXOnePar(Buffer const & buf,
 	// Do not output empty commands if the whole paragraph has
 	// been deleted with ct and changes are not output.
 	if (!runparams_in.for_search && style.latextype != LATEX_ENVIRONMENT
-	    && par.isDeleted(0, par.size()) && !bparams.output_changes)
+	    && par.size() > 0 && par.isDeleted(0, par.size()) && !bparams.output_changes)
 		return;
 
 	LYXERR(Debug::LATEX, "TeXOnePar for paragraph " << pit << " ptr " << &par << " '"