This is the known stable-sort problem. Sadly we have no plan what to do about it to reduce the noise.

// Simpler repro:
a = [];
// Depends on array length, doesn't trigger with e.g. 1000 only.
// a[1000] = null;
a[5000] = null;
a[30] = 0;
Array.prototype.sort.call(a, function(b) { return true; });
print(a[0]);
print(a[1]);

// Output:
# Compared x64,ignition with ia32,ignition
#
# Flags of x64,ignition:
--abort_on_stack_overflow --expose-gc --allow-natives-syntax --invoke-weak-callbacks --omit-quit --es-staging --random-seed 732681078 --ignition --turbo-filter=~ --hydrogen-filter=~ --nocrankshaft
# Flags of ia32,ignition:
--abort_on_stack_overflow --expose-gc --allow-natives-syntax --invoke-weak-callbacks --omit-quit --es-staging --random-seed 732681078 --ignition --turbo-filter=~ --hydrogen-filter=~ --nocrankshaft
#
# Difference:
- 0
+ null
#
### Start of configuration x64,ignition:
0
null

### End of configuration x64,ignition
#
### Start of configuration ia32,ignition:
null
0

### End of configuration ia32,ignition

ClusterFuzz has detected this issue as fixed in range 45316:45317.

Detailed report: https://clusterfuzz.com/testcase?key=6323235533881344

Fuzzer: foozzie_js_mutation
Job Type: v8_foozzie
Platform Id: linux

Crash Type: V8 correctness failure
Crash Address: 
Crash State:
  configs: x64,ignition:ia32,ignition
  sources: a10
  
Sanitizer: address (ASAN)

Fixed: V8: 45316:45317

Reproducer Testcase: https://clusterfuzz.com/download?testcase_id=6323235533881344


See https://dev.chromium.org/Home/chromium-security/bugs/reproducing-clusterfuzz-bugs for more information.

If you suspect that the result above is incorrect, try re-doing that job on the test case report page.