For anyone who knows more about hard faults, note that what I posted in the embassy channel mentioned the output of two hard-fault related registers:
```
            read 0xE000ED28
            0xe000ed28 = 0x00020000

That apparently means there was an INVSTATE condition, possibly from some assembly that didn't set bit 0 of some instruction in thumb mode. (I don't have any custom assembly in here, so that could be a compiler bug I guess, if this means anything.)

            read 0xE000ED2C
            0xe000ed2c = 0x40000000

This bit in the HFSR says "FORCED - This means a configurable fault (i.e. the fault types we discussed in previous sections) was escalated to a HardFault, either because the configurable fault handler was not enabled or a fault occurred within the handler."
```