I've reduced my design to its smallest size and I'm still getting

Notice 0: Finished DEF file: /project/openlane/user_proj_example/runs/user_proj_example/results/routing/user_project_example.def
Notice 0: Split top of 6982 T shapes.
Number of pins violated: 201
Number of nets violated: 156
Total number of nets: 21913

What's it trying to tell me?

it's trying to say that you have antenna violations on 201 pins and 156 nets.

@Jean: Try different antenna solver algorithms for the DIODE_INSERTION_STRATEGY parameter (0,1,2,3)

With strategy 3, it segfaults! Reducing density.

[WARNING] Pin wbs_dat_i[17] is outside die area
[WARNING] Pin wbs_dat_i[18] is outside die area
[WARNING] Pin wbs_dat_i[19] is outside die area
[WARNING] Pin wbs_dat_i[1] is outside die area
[WARNING] Pin wbs_dat_i[20] is outside die area
[WARNING] Pin wb[ERROR]: during executing: "openroad -exit /openLANE_flow/scripts/openroad/or_route.tcl |& tee >&@stdout /project/openlane/user_proj_example/runs/user_proj_example/logs/routing/fastroute.log"
[ERROR]: Exit code: 1
[ERROR]: Last 10 lines:
child killed: segmentation violation