Error: could not resolve parametric type of accumulator: could not resolve interface type

[TsubasaEX]

Hi there,

I found an interesting issue here.
When I try to set a breakpoint in the reduce function, the library shows error messages, but the result is okay.
However, if I don't set any breakpoints in the reduce function, it works fine with no error messages.
Is it related to some kinds of the internal issues in the library itself?

Thanks in advance.