My car's windshield was hit by a small rock on highway and got a dark spot and
a small crack (shape is like a "L", 3mm and 6mm).

I went to Auto Glass and they said they can't gurantee that they can repair it
'cause the repair procedure might make the crak bigger.

Can anyone share your car Glass repairing experience, please?

Under what kind of situations will the crack turn bigger? And how to avoid it
turing bigger?

Will this be safe to continue driving the car without repairing the Glass?

thx a lot!!!