[nextpnr_fpga_interchange] ERROR: Assert ctx->checkRoutedDesign() failed

[clavin-xlnx]

Although nextpnr_fpga_interchange terminates with Info: Program finished normally., it also has the error message:

ERROR: Assert ctx->checkRoutedDesign() failed

The design targets the same part as the ZCU104 board and consists of just LUTs and FFs. Here is the command I used to reproduce (design files and full log
retarget_example.zip
attached):

fpga-interchange-tests/env/conda/envs/fpga-interchange/bin/nextpnr-fpga_interchange --chipdb fpga-interchange-tests/build/devices/xczu7ev/xczu7ev.bin --netlist retarget_gnl.netlist --phys retarget_gnl_nextpnr.phys --package ffvc1156 --log retarget_gnl_nextpnr.log --disable-lut-mapping-cache  --xdc retarget_gnl.xdc