Your solution falls into an infinite loop for following test case: assert.deepEqual(mergeArrays([ -3, -2, -1, 0 ], [ 1, 2, 3, 4 ]), [ -3, -2, -1, 0, 1, 2, 3, 4 ]);.
Your solution has a bug, it's not a kata issue.

Hi! I receive the error:

Fatal error in , line 0

Fatal JavaScript invalid size error 169220804

#FailureMessage Object: 0x7ffda2482340
1: 0xbd7061 [node]
2: 0x1dfa6b4 V8_Fatal(char const*, ...) [node]
3: 0xeeb3a8 [node]
4: 0x10997b2 [node]
5: 0x1099a75 [node]
6: 0x12a813b v8::internal::Runtime_GrowArrayElements(int, unsigned long*, v8::internal::Isolate*) [node]
7: 0x16e99f9 [node]

I tested my code with any combinations of arrays including empty. I can get the same error in my IDE if I send as argument just number instead array. Is it all Ok with tests? Is it possible to get all tests?