Issue Resolved by the mod creator. (Thank you again!)

Error while running event
017_science::on_plyaer_cursur_stack_changed (ID 29)
__017_science_/control.lua:110: attempt to index global 'highest_speed' (a nil value)

Can't play my current save from the current update as of 11/01/2019

were you running any mods? I tested the pickaxe functionality by joining an old world and it seemed to work. In the next update I put in a catch for the highest_speed value so that if it's nil it'll regenerate the table. If this all doesn't work there should be an option to disable the pickaxe logic and use the old method of manually crafting them.

Yes I do have other mods. It's either one of those interfering with your code. Could it be that I already had 5 pickaxes in the slot when I updated the your mod? When I press Q on the tool belt or anywhere it throws that error.

The pickaxes should not be a problem (they just get absorbed into the infinite pickaxe). I'm going to release 0.0.11 in a few mins, see if that fixes the issue.

I will let you know!

The problem is resolved! You're awesome! I can get back to work on my megabase.

Thank you for your feedback! knew i had something missing from that spaghetti code...

I thought it was still broken but I found that Factorio is not updating the mod correctly. It said it updated to the latest but when I re-entered the game it still crashed. I had to exit the game and manually download and update the mod. Now everything is working again. I wonder if the Factorio mod update system is bugged. Thanks for the quick fix.