Fix lineno options param

This has been written even if empty -- and thus caused reading errors.

lib/doc/Customization.lyx

@@ -103,7 +103,6 @@ logicalmkup
 \use_refstyle 0
 \use_minted 0
 \use_lineno 0
-\lineno_options 
 \notefontcolor #0000ff
 \branch OutDated
 \selected 0

lib/doc/UserGuide.lyx

@@ -118,7 +118,6 @@ logicalmkup
 \use_refstyle 1
 \use_minted 0
 \use_lineno 0
-\lineno_options 
 \notefontcolor #0000ff
 \branch Question
 \selected 1

lib/doc/de/Customization.lyx

@@ -111,7 +111,6 @@ logicalmkup
 \use_refstyle 0
 \use_minted 0
 \use_lineno 0
-\lineno_options 
 \notefontcolor #0000ff
 \branch OutDated
 \selected 0

lib/doc/de/UserGuide.lyx

@@ -123,7 +123,6 @@ logicalmkup
 \use_refstyle 1
 \use_minted 0
 \use_lineno 0
-\lineno_options 
 \notefontcolor #0000ff
 \branch Frage
 \selected 1

lib/lyx2lyx/lyx_2_4.py

@@ -1721,8 +1721,11 @@ def convert_lineno(document):
             del_token(document.preamble, "% Added by lyx2lyx", j-2, j-1)
 
     k = find_token(document.header, "\\index ")
-    document.header[k:k] = ["\\use_lineno %d" % use_lineno,
+    if options == "":
-                            "\\lineno_options %s" % options]
+        document.header[k:k] = ["\\use_lineno %d" % use_lineno]
+    else:
+        document.header[k:k] = ["\\use_lineno %d" % use_lineno,
+                                "\\lineno_options %s" % options]
 
 
 ##

src/BufferParams.cpp

@@ -1329,7 +1329,8 @@ void BufferParams::writeFile(ostream & os, Buffer const * buf) const
 	   << "\n\\use_lineno " << use_lineno
 	   << '\n';
 
-	 os << "\\lineno_options " << lineno_opts << '\n';
+	if (!lineno_opts.empty())
+		os << "\\lineno_options " << lineno_opts << '\n';
 
 	if (isbackgroundcolor == true)
 		os << "\\backgroundcolor " << lyx::X11hexname(backgroundcolor) << '\n';