Internal Error and klipper shutdown caused by -inf reading.

[keyz182]

11:25:17	Internal error on command:"QUAD_GANTRY_LEVEL"
11:25:17	Internal error on command:"BTT_QUAD_GANTRY_LEVEL"
11:25:16	Klipper state: Shutdown
11:25:15	Making the following Z adjustments:
stepper_z = nan
stepper_z1 = nan
stepper_z2 = nan
stepper_z3 = nan
11:25:15	Average: nan
11:25:14	Actuator Positions:
z: -00inf z1: 000nan z2: 000nan z3: 000nan
11:25:14	Gantry-relative probe points:
0: -inf 1: 16.807169 2: -inf 3: -inf
11:25:14	probe at 300.000,25.000,1.638 is z=-inf
11:25:05	probe at 300.000,275.000,1.938 is z=-inf
11:24:55	probe at 50.000,275.000,1.798 is z=0.605669
11:24:46	probe at 50.000,25.000,1.703 is z=-inf
11:24:40	QUAD_GANTRY_LEVEL

There are two errors in this console log:

1. probe is returning -inf
2. -inf is being passed through to calculations for the QGL.

Error 2 is what I'm reporting here - this issue just popped up so I haven't started troubleshooting 1, but likely something silly my side.

I think BeaconProbe._probe could have a check on dist added to see if it's in a "reasonable" range, and abort at that point rather than try to continue. What a "reasonable" range would be is entirely up for debate, but could at least be "not infinity" :)

I've got a snapshot of my configs I can roll back to if more info is required.