Program received signal SIGSEGV, Segmentation fault.
nextpnr_xilinx::XilinxPacker::pack_constants (this=<optimized out>)
    at /home/ricola/Downloads/fpga/esden/test/nextpnr-xilinx/xilinx/pack.cc:491
491	        if (ni->driver.cell != nullptr && ni->driver.cell->type == ctx->id("GND")) {