There also may be hidden requirements such as they pass in a different data/var type and it could through off the code. For instances like this if you truly believe its an error you can raise an issue in the kata and see if it gets fixed, otherwise it may be an edge case.

If the errors are not traceables but because of the test, then the test conditions must be met, which are sometimes not written in the instructions.

You are right. I didnt notice.
But this is just one of many examples.

You're NOT supposed to post your code publicly.

I can execute them on my IDE perfectly

Name at least one IDE/compiler which would allow you to modify a constant string, or stop talking nonsense if you can't.

This is a very simple kata where i just make a string to be uppercase.

std::string makeUpperCase (const std::string& input_str)
{

std::transform (input_str.begin(), input_str.end(), std::toupper);

return input_str;
}

or

for (int i = 0; i < str.length(); i++)
{
str[i] = std::toupper(str[i]);
}

They both dont work
Obviously, there is always a reason for these errors to be there. Its just that they work in my IDE and this is such simple code. Very annoying.

Can you give an example?

There are so many katas that i can perfectly solve in my IDE, but not on codewars. I have to skip many simple katas because of errors im getting, even though the logic and code is appereantly fine, since i can execute them on my IDE perfectly. Its obnoxious to not be able to complete the kata when the implemented compiler is giving me an error for a single-line program.
Is there anything i can do about that? Sorry for the dumb question