Fixed the issue! I can now update Smartly Inject and don't get an error. I also tried a clean install of Hubigraphs using HPM and that worked, too.
My solution: use HPM to run a repair on itself.
Something must have been corrupt in the original install, but I can't for the life of me figure out how I messed it up. The version # at the top of the file I copied into the apps code from Github was the latest (1.7.0). No diff function available, so I can't tell what changed.
At any rate, if you're having trouble with HPM and Smartly Inject or Hubigraphs, try running a repair on HPM from the HPM menu!
