Fix Lua tag_index return values

RELEASE_NOTES.md

@@ -153,6 +153,10 @@ changes (where available).
 - Check added to ensure view has changed before processing GUI events
   preventing hang on start.
 
+- return an empty table (nil) for a non-existent tag accessed by index
+
+- return an empty table (nil) when a tag contains no images with the tag
+
 ### Add action support for Lua
 
 ### Other Lua changes

src/lua/tags.c

@@ -92,7 +92,8 @@ static int tag_index(lua_State *L)
   int index = luaL_checkinteger(L, -1);
   if(index < 1)
   {
-    return luaL_error(L, "incorrect index in database");
+    lua_pushnil(L);
+    return 1;
   }
   sqlite3_stmt *stmt = NULL;
   char query[1024];
@@ -107,8 +108,7 @@ static int tag_index(lua_State *L)
   }
   else
   {
-    sqlite3_finalize(stmt);
-    luaL_error(L, "incorrect index in database");
+    lua_pushnil(L);
   }
   sqlite3_finalize(stmt);
   return 1;