You are right. It should not raise an exception.
Luckily the tests don't contain invalid chars, so this solution passes.

Please clarify the description:
"... when they are an exact match, and appending the second string to the first if they are not.
NOTE: The strings may be empty."

Because these cases are not really clear from the given examples.
Thank you!

At least Python: All test cases count 1 extra divisor, which is wrong.

Even the kata description is wrong: there are 70 not 71 factors in the example list: [2, 3, 4, 5, 6, 8, 9, 10, 12, 13, 15, 18, 20, 24, 25, 26, 30, 36, 39, 40, 45, 50, 52, 60, 65, 72, 75, 78, 90, 100, 104, 117, 120, 130, 150, 156, 180, 195, 200, 225, 234, 260, 300, 312, 325, 360, 390, 450, 468, 520, 585, 600, 650, 780, 900, 936, 975, 1170, 1300, 1560, 1800, 1950, 2340, 2600, 2925, 3900, 4680, 5850, 7800, 11700].

Python: the instructions should of course say that 2 <= m < n <= 11000000

string "6F43E8" must throw "Error" like instructions say at the end.

Java translation
https://www.codewars.com/kumite/6377c8af0ab4f00057e3580e?sel=6377c8af0ab4f00057e3580e

Please approve it. Thank you.
I also clarified and improved the instructions, as many people here have wished.

Yes, it is. But the instructions are not clear enough.

To clarify: Please print the input. '6F43E8' is not the input of the test where your code is failing.
Read this: https://docs.codewars.com/training/troubleshooting/#print-input
Your code fails another test case.
Also if you select Node v8.1.3 you may get clearer error messages.

Yes, I made the same experience.
I have translated it to Java. I proposed to clarify the instructions.

You are correct. Unfortunately I can't change it. I am still working up my honor points.

That may be so, but Codewars is a kind of sport. Performance katas are like a race.

[Python] Unfortunately the serious test always aborts with an error message because of the test code:
/workspace/default/tests.py:7: DeprecationWarning: np.bool is a deprecated alias for the builtin bool. To silence this warning, use bool by itself. Doing this will not modify any behavior and is safe. If you specifically wanted the numpy scalar type, use np.bool_ here.
Deprecated in NumPy 1.20; for more details and guidance: https://numpy.org/devdocs/release/1.20.0-notes.html#deprecations
sieve = numpy.ones(n//3 + (n%6==2), dtype=numpy.bool)
Traceback (most recent call last):
File "/workspace/default/tests.py", line 54, in
result = f_sol(n)
File "/workspace/default/tests.py", line 36, in f_sol
max_even_digs = max(resDict.keys())
TypeError: 'int' object is not callable