gnucash master: Fix crash in case filter is less than 4 parameters

[Geert Janssens]

Updated	 via  https://github.com/Gnucash/gnucash/commit/9df81fa7 (commit)
	from  https://github.com/Gnucash/gnucash/commit/3e44af3c (commit)



commit 9df81fa7abea542c76faa6d2772226bc018b875f
Author: Geert Janssens <geert at kobaltwit.be>
Date:   Wed May 13 15:27:00 2020 +0200

    Fix crash in case filter is less than 4 parameters
    
    This apparently is not an issue on maint, but on master it results in a crash.



Summary of changes:
 gnucash/gnome/gnc-plugin-page-register.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)