Please post the crash report (use a site like https://hastebin.com, don't paste it in a comment).
Debugging crashes is basically impossible without one unless the issue is already known, and you are the first person I see crashing from this.
I accidentally did this the other day. Here's how I fixed it. Download MCEdit, load up your world, and open up the player editor (may not be the exact name). Select your character, and change the jarred node in your inventory to stone or something. Then save the world, close it, close MCEdit, and it should load back up in Minecraft.
Close. Looks like a common source for both. A little digging pointed out that Game-icons also pulls from Lorc's 700+ RPG Icons set. The attribution line for this is in the MCF thread: "Lorc, creator of the icons I use for enchanting and other things"
I'm definitely a fan of CC licensed stuff. A lot of good artwork showing up in various places.
Thanks for pointing this out. This is an excelent resource.
If you want a good text editor, I'd look into VS Code. Despite "VS" (for "Visual Studio") in the name, it's a completely separate product from Visual Studio. It's cross-platform, so it runs on Linux, Max and Windows, and it combines good text-editor features with a lot of "IDE Lite" features that make development easy. (There are plugins for most major languages). It's actually what I use day-to-day for my regular C# coding job.