The stack inserter wasn't working, so I created a fix. It might not be perfect, but it functions properly.

local fast = util.table.deepcopy(data.raw["inserter"]["stack-inserter"])
fast.name = "ultra-fast-stack-inserter"
fast.icon = data.raw["inserter"]["stack-inserter"].icon
fast.icon_size = data.raw["inserter"]["stack-inserter"].icon_size
fast.flags = {"placeable-neutral", "placeable-player", "player-creation"}
fast.hand_size = 1.5
fast.minable.result = "ultra-fast-stack-inserter"
fast.pickup_position = {0, -1}
fast.insert_position = {0, 1.2}
fast.extension_speed = 20
fast.rotation_speed = 20
fast.fast_replaceable_group = "inserter"

fast.hand_base_picture = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

fast.hand_base_shadow = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

fast.hand_closed_picture = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

fast.hand_closed_shadow = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

fast.hand_open_picture = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

fast.hand_open_shadow = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
hr_version = {
filename = "base/graphics/entity/bulk-inserter/bulk-inserter-hand-base.png",
height = 1,
priority = "extra-high",
scale = 0.25,
width = 1,
visible = false
},
priority = "extra-high",
width = 1,
visible = false
}

data:extend({fast})