Make sure we have a file to work with in the derivative generator

Author: Floppy

app/uploaders/application_uploader.rb

@@ -25,6 +25,18 @@ class ApplicationUploader < Shrine
     downloads: Shrine::Storage::FileSystem.new("tmp/downloads")
   }
 
+  F3D_OPTS = {
+    output: "-",
+    resolution: "512,512",
+    filename: "0",
+    "background-color": "0,0,0",
+    "ambient-occlusion": "1",
+    "grid-unit": "10",
+    "grid-color": "0,255,255",
+    "grid-subdivisions": 0,
+    axis: "0"
+  }.map { |k, v| "--#{k}=#{v}" }.join(" ").freeze
+
   storage(/library_(\d+)/) do |m|
     Library.find(m[1]).storage # rubocop:disable Pundit/UsePolicyScope
   rescue ActiveRecord::RecordNotFound
@@ -101,21 +113,12 @@ def generate_location(io, record: nil, derivative: nil, metadata: {}, **)
         }
       end
     elsif SupportedMimeTypes.can_render?(context[:record].mime_type)
-      f3d_opts = {
-        output: "-",
-        resolution: "512,512",
-        filename: "0",
-        "background-color": "0,0,0",
-        "ambient-occlusion": "1",
-        "grid-unit": "10",
-        "grid-color": "0,255,255",
-        "grid-subdivisions": 0,
-        axis: "0"
-      }.map { |k, v| "--#{k}=#{v}" }.join(" ").freeze
-      render = StringIO.new(`f3d #{original.path} #{f3d_opts}`)
-      {
-        render: (render.length > 0) ? render : nil
-      }.compact
+      Shrine.with_file(original) do |it|
+        render = StringIO.new(`f3d #{it.path} #{F3D_OPTS}`)
+        {
+          render: (render.length > 0) ? render : nil
+        }.compact
+      end
     else
       {}
     end