FIX: Ignore invalid images when shrinking uploads (discourse#25346)

lib/shrink_uploaded_image.rb

@@ -40,7 +40,11 @@ def perform
       return false
     end
 
-    w, h = FastImage.size(path, timeout: 15, raise_on_failure: true)
+    begin
+      w, h = FastImage.size(path, timeout: 15, raise_on_failure: true)
+    rescue FastImage::SizeNotFound
+      return false
+    end
 
     if !w || !h
       log "Invalid image dimensions after resizing"

spec/lib/shrink_uploaded_image_spec.rb

@@ -110,6 +110,21 @@
 
       expect(result).to be(false)
     end
+
+    it "returns false if the image is invalid" do
+      post = Fabricate(:post, raw: "<img src='#{upload.url}'>")
+      post.link_post_uploads
+      FastImage.stubs(:size).raises(FastImage::SizeNotFound.new)
+
+      result =
+        ShrinkUploadedImage.new(
+          upload: upload,
+          path: Discourse.store.path_for(upload),
+          max_pixels: 10_000,
+        ).perform
+
+      expect(result).to be(false)
+    end
   end
 
   context "when S3 uploads are enabled" do