If you can handle an error and still return meaningful data that's fine, but returning the coordinates 0,0 to the user because GPS isn't working is far worse than giving them an error message. At that point you're essentially lying to them.
To a certain extent, all gps data is lying to you, it’s about figuring out how much it’s lying to you, sticking something at 0,0 is fairly tame and much easier to detect than something being out by 5cm
We do indicate to the user in the ui if no gps signal is available for example, or it’s low quality, but sometimes we get things like the system reporting it’s current location as the estimated location of the last wifi connection.
We also might start something and have no gps, but acquire it later, could be seconds, minutes or never, the accuracy can increase and decrease, we don’t force the user to give up, we record what we can. we still face limitations from software further down the chain that require coordinates as inputs.