Flang: REPEAT has negative NCOPIES=-1

With flang-new (flang version 20.1.3) I get the error:

```
fatal Fortran runtime error(json_value_module.F90:11432): REPEAT has negative NCOPIES=-1
<ERROR> Execution for object " jf_test_01.exe " returned exit code  -1073740791
<INFO> *cmd_run*:stopping due to failed executions
STOP -1073740791
```

This is on Windows.

A real bug or compiler bug?