FIX: empty uploads and blank filenames caused errors during validation

lib/upload_creator.rb

@@ -21,9 +21,9 @@ class UploadCreator
   #  - for_private_message (boolean)
   #  - pasted (boolean)
   def initialize(file, filename, opts = {})
-    @upload = Upload.new
     @file = file
-    @filename = filename
+    @filename = filename || ''
+    @upload = Upload.new(original_filename: filename, filesize: 0)
     @opts = opts
   end
 

spec/models/upload_spec.rb

@@ -51,6 +51,13 @@ describe Upload do
     expect(created_upload.extension).to eq("png")
   end
 
+  it "should create an invalid upload when the filename is blank" do
+    SiteSetting.authorized_extensions = "*"
+
+    created_upload = UploadCreator.new(image, nil).create_for(user_id)
+    expect(created_upload.valid?).to eq(false)
+  end
+
   context ".get_from_url" do
     let(:url) { "/uploads/default/original/3X/1/0/10f73034616a796dfd70177dc54b6def44c4ba6f.png" }
     let(:upload) { Fabricate(:upload, url: url) }