Bug #59498 div function broken in mysql-trunk

mysql-test/r/func_math.result:
  New test case.
mysql-test/t/func_math.test:
  New test case.
sql/item_func.cc:
  Check for null before converting value to my_decimal.

mysql-test/r/func_math.result

@@ -650,3 +650,9 @@ SELECT ((@a:=@b:=1.0) div (@b:=@a:=get_format(datetime, 'usa')));
 NULL
 Warnings:
 Warning	1366	Incorrect decimal value: '' for column '' at row -1
+#
+# Bug #59498 div function broken in mysql-trunk
+#
+SELECT 1 div null;
+1 div null
+NULL

mysql-test/t/func_math.test

@@ -495,3 +495,8 @@ DROP TABLE t1;
 --echo #            in do_div_mod with doubly assigned variables
 --echo #
 SELECT ((@a:=@b:=1.0) div (@b:=@a:=get_format(datetime, 'usa')));
+
+--echo #
+--echo # Bug #59498 div function broken in mysql-trunk
+--echo #
+SELECT 1 div null;

sql/item_func.cc

@@ -1582,10 +1582,15 @@ longlong Item_func_int_div::val_int()
       args[1]->result_type() != INT_RESULT)
   {
     my_decimal tmp;
-    my_decimal val0= *args[0]->val_decimal(&tmp);
-    my_decimal val1= *args[1]->val_decimal(&tmp);
-    if ((null_value= (args[0]->null_value || args[1]->null_value)))
+    my_decimal *val0p= args[0]->val_decimal(&tmp);
+    if ((null_value= args[0]->null_value))
       return 0;
+    my_decimal val0= *val0p;
+
+    my_decimal *val1p= args[1]->val_decimal(&tmp);
+    if ((null_value= args[1]->null_value))
+      return 0;
+    my_decimal val1= *val1p;
 
     int err;
     if ((err= my_decimal_div(E_DEC_FATAL_ERROR & ~E_DEC_DIV_ZERO, &tmp,