UPDATE: It was my MZ Core Script being out of date that caused the issue! As of this writing, updating it to 1.7.0 (the latest version) did the trick.
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ORIGINAL POST
Basically what the title says. I try to load up my game w/ the plugin enabled, and I can't even get into the game, instead having this error thrown up at me. I already have Eli Book in my game and placed above the Picture Manager, so it's not that. I don't think it's a plugin conflict either - I had all my plugins except Book and Picture Manager disabled, and I still got the error.
Your sample project with Picture Manager dragged into it works fine, too, so I'm privvy to believe that I might have a plugin missing. Is there any other plugin besides Eli Book I need?