Topic category: Troubleshooting, bugs, and solutions
Step 1: Create the mob, add the tasks you wish to add that involve any interactions with EntityPlayer.
Step 2: You WILL get a crash, but ignore it.
Step 3: Edit the code of the mob.
Step 4: Scroll down a bit in the code until you find a section similar to this: https://gyazo.com/fcae61c125283c9222e46ea4b26bd924
Step 5: Where you see "EntityEntityPlayer.class", Remove the one of the "Entity" words from it so it should say "EntityPlayer." Here's an example: https://i.gyazo.com/8fa7dad02b304cb4ae3112c32b78b233.mp4
Step 6: IF there are any other "this.tasks.addtask" with the "EntityEntityPlayer.class" Just do the same thing. It should work, just click "Save and Recompile" up at the top of the tab.
If there are any issues, reply to this, and I can try to clear up any confusion.
This solution works ONLY on MCreator 1.6.9 for Minecraft 1.9.4, This may NOT be necessary for earlier versions.