"getLengthOfMissingArray" is the name of function you have to write, so the error message is pointing to code that is written by you.

Somewhere in your code, you are trying to access .length on something that is null (we can only guess where it comes from, without seeing your code).

Make use of console.logs to see where this happens.

main test passes without errors.

send attemp : value passed - always different 28 or 32 or 36

Time: 835ms Passed: 33Failed: 10 Errors: 1Exit Code: 10

TypeError: Cannot read property 'length' of null
at getLengthOfMissingArray (test.js:4:9)
at Context. (test.js:38:24)
at processImmediate (internal/timers.js:464:21)

what could be the reason for the test or my code ?

I enjoyed this kata, thanks for putting it together.

javaScript .
thanks.

I have already found a solution.

In which language?

I only fail Fixed Tests where I can see Fixed Tests.
Input Validation Tests -> true
Random Tests -> true

I don't understand what this error means

Basic tests
Test Passed: Value == 'TestCase'
Test Passed: Value == 'CamelCaseMethod'

TypeError: Cannot read property 'toLocaleUpperCase' of undefined
at sdd.forEach
at Array.forEach
at String.camelCase
at describe
at /runner/frameworks/javascript/cw-2.js:152:11
at Promise._execute
at Promise._resolveFromExecutor
at new Promise
at describe
at /home/codewarrior/index.js:18:5
at /home/codewarrior/index.js:25:5
at Object.handleError

one and the same letter but different registers is also a duplicate thanks .already fixed everything works)

Don't worry about that, in C++ true and 1 and false and 0 are equivalent (for a boolean). Your problem is your code isn't ignoring capitalization, read again the example with moOse as input .

one and the same letter but different registers is also a duplicate thanks

The example in the description shows what "ignore letter case" means:

isIsogram("moOse") == false // -- ignore letter case

An isogram is a word that has no repeating letters, consecutive or non-consecutive.

There are two o in "moOse" (ignoring letter case they're equal).

the case of letters is ignored.

Your code fails with this test for example:

Assert::That(is_isogram("moOse"), Equals(false));