patch 8.2.1848: crash when passing a NULL string or list to popup_settext()

Problem:    Crashyyyyy passing a NULL string or list to popup_settext().
Solution:   Check for NULL pointers. (closes #7132)

src/version.c

@@ -750,6 +750,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1848,
 /**/
     1847,
 /**/