a++ on a local variable should it fail

[Raja Nagendra Kumar]

On a code like this

public final class EmployeeFixed
{
private final String id;
private String name;
private double salary;

public EmployeeFixed(final String aNewId, final String aNewName, final double aNewSalary)
{
id = aNewId;
setName(aNewName);
setSalary(aNewSalary);
}

I see Mutation test services and reports it as an error

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3. Incremented (a++) double local variable number 3 → SURVIVED

4. Decremented (a--) double local variable number 3 → SURVIVED

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Why a++ and a-- should fail, as it is local variable increment and it happens after the operation is completed.. Is this an issue pit framework itself to see a++, a-- as a mutation that should fail?