PocketType - Espruino Bluetooth Keyboard & Display

I have built the promicro. Hex-file according:
make clean && BOARD=PROMICRO RELEASE=1 make
Then build the promicro.uf2 file:
uf2conv.py espruino_2v25.13_promicro.hex -b 0x26000 --family 0xADA52840 --convert --output espruino_2v25.13_promicro.uf2

Checking the file with uf2conv.py -i espruino_2v25.13_promicro.uf2 results in error:

Traceback (most recent call last):
File "C:\Users\louis\projecten\espruino\Espruino\bin\uf2conv.py", line 361, in

main()

File "C:\Users\louis\projecten\espruino\Espruino\bin\uf2conv.py", line 329, in main

convert_from_uf2(inpbuf)

File "C:\Users\louis\projecten\espruino\Espruino\bin\uf2conv.py", line 71, in convert_from_uf2

assert False, "More than 10M of padding needed at " + ptr
              ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~

TypeError: can only concatenate str (not "int") to str

When I do the same procedure for the NRF52840DK.py, then everything goes well