Missing Dependency SourceEntity

I am trying to make a vein miner type mod, and I am using a recursive procedure every time you break a block with a certain tool. For some reason, the procedure needs the sourceentity. The only blocks I use are [get block], [is block tagged in tags as], [remove block and drop at], [x], [y], [z], [if], [call procedure] (itself), and math blocks. Which requires sourceentity?