Loading menu locks up when loading EPR and have to hard shutdown game. Mystical Forestry 0.1.2. 0.0.1 works fine though.
https://mods.factorio.com/mod/ExpandedProductivityResearch

So while I can't reproduce the error I can already assume why that could happen Mystical Forestry can add quite a lot of recipe and research, dependent if quality plant seed and upgrading is enabled or not, and I think EPR has to sift through all that to add the productivity which might be quite taxing hence the hard locking of the game.
0.0.1 has basically nothing when it comes to recipes and research so it make sense that it works well.
Having said that I don't think I'm qualified enough to make a fix or patch for that so a fix will have to wait until i figure that out sorry

So while I can't reproduce the error I can already assume why that could happen Mystical Forestry can add quite a lot of recipe and research, dependent if quality plant seed and upgrading is enabled or not, and I think EPR has to sift through all that to add the productivity which might be quite taxing hence the hard locking of the game.
0.0.1 has basically nothing when it comes to recipes and research so it make sense that it works well.
Having said that I don't think I'm qualified enough to make a fix or patch for that so a fix will have to wait until i figure that out sorry

No idea what you did. But 0.1.3 works with EPR and game without issues now.