MDEV-22141: JSON_REMOVE returns NULL on valid arguments

Analysis:
When we scan json to get to a beginning according to the path, we end up
scanning json even if we have exhausted it. When eventually returns error.

Fix:
Continue scanning json only if we have not exhausted it and return result
accordingly.

mysql-test/main/func_json.result

@@ -1711,5 +1711,11 @@ NULL
 Warnings:
 Warning	4038	Syntax error in JSON text in argument 1 to function 'json_type' at position 5
 #
+# MDEV-22141: JSON_REMOVE returns NULL on valid arguments
+#
+SELECT JSON_REMOVE('{"A": { "B": 1 }}', '$.A.B.C.D');
+JSON_REMOVE('{"A": { "B": 1 }}', '$.A.B.C.D')
+{"A": {"B": 1}}
+#
 # End of 10.5 tests
 #

mysql-test/main/func_json.test

@@ -1140,6 +1140,13 @@ DROP TABLE t;
 SELECT JSON_TYPE(json_value(JSON_OBJECT("id", 1, "name", 'Monty', "date", Cast('2019-01-01' as Date) ), '$.date'));
 
 
+--echo #
+--echo # MDEV-22141: JSON_REMOVE returns NULL on valid arguments
+--echo #
+
+SELECT JSON_REMOVE('{"A": { "B": 1 }}', '$.A.B.C.D');
+
+
 --echo #
 --echo # End of 10.5 tests
 --echo #

sql/item_jsonfunc.cc

@@ -3332,6 +3332,7 @@ String *Item_func_json_remove::val_str(String *str)
     {
       if (je.s.error)
         goto js_error;
+      continue;
     }
 
     if (json_read_value(&je))