render plain text file if the LFS object doesn't exist (#31812)

We had an issue where a repo was using LFS to store a file, but the user
did not push the file. When trying to view the file, Gitea returned a
500 HTTP status code referencing `ErrLFSObjectNotExist`. It appears the
intent was the render this file as plain text, but the conditional was
flipped. I've also added a test to verify that the file is rendered as
plain text.

6 files changed, 16 insertions, 1 deletions

diff --git a/tests/gitea-repositories-meta/user2/lfs.git/objects/30/77e1c4c8964613df72c37d14275c1eda5228a9 b/tests/gitea-repositories-meta/user2/lfs.git/objects/30/77e1c4c8964613df72c37d14275c1eda5228a9
new file mode 100644
index 0000000000..c2dc6e5a4f
--- /dev/null
+++ b/tests/gitea-repositories-meta/user2/lfs.git/objects/30/77e1c4c8964613df72c37d14275c1eda5228a9
@@ -0,0 +1,2 @@
+x
KÊÉOR0´0`pö÷	òt
+
ñôs×ËMQHËÌ)I-²ÍI+VHÉLK3rS‹ÒSÁ,Ý’ÔŠ.-½¬‚t"U&eæ¥23¯,1'“8û
ØæAÅ
\ No newline at end of file
diff --git a/tests/gitea-repositories-meta/user2/lfs.git/objects/6b/bc79965141058b0026f2064dfb6d2eae3c4540 b/tests/gitea-repositories-meta/user2/lfs.git/objects/6b/bc79965141058b0026f2064dfb6d2eae3c4540
new file mode 100644
index 0000000000..97455cbc46
--- /dev/null
+++ b/tests/gitea-repositories-meta/user2/lfs.git/objects/6b/bc79965141058b0026f2064dfb6d2eae3c4540
diff --git a/tests/gitea-repositories-meta/user2/lfs.git/objects/b0/89e97ee59224e8c5676673c096ee4b6a8b9342 b/tests/gitea-repositories-meta/user2/lfs.git/objects/b0/89e97ee59224e8c5676673c096ee4b6a8b9342
new file mode 100644
index 0000000000..33ab64e730
--- /dev/null
+++ b/tests/gitea-repositories-meta/user2/lfs.git/objects/b0/89e97ee59224e8c5676673c096ee4b6a8b9342
diff --git a/tests/gitea-repositories-meta/user2/lfs.git/objects/e9/c32647bab825977942598c0efa415de300304b b/tests/gitea-repositories-meta/user2/lfs.git/objects/e9/c32647bab825977942598c0efa415de300304b
new file mode 100644
index 0000000000..f513e2a308
--- /dev/null
+++ b/tests/gitea-repositories-meta/user2/lfs.git/objects/e9/c32647bab825977942598c0efa415de300304b
diff --git a/tests/gitea-repositories-meta/user2/lfs.git/refs/heads/master b/tests/gitea-repositories-meta/user2/lfs.git/refs/heads/master
index 8832a3e857..487a433af2 100644
--- a/tests/gitea-repositories-meta/user2/lfs.git/refs/heads/master
+++ b/tests/gitea-repositories-meta/user2/lfs.git/refs/heads/master
@@ -1 +1 @@
-73cf03db6ece34e12bf91e8853dc58f678f2f82d
+e9c32647bab825977942598c0efa415de300304b
diff --git a/tests/integration/lfs_view_test.go b/tests/integration/lfs_view_test.go
index c28ecf1d7a..05770e5e0a 100644
--- a/tests/integration/lfs_view_test.go
+++ b/tests/integration/lfs_view_test.go
@@ -89,6 +89,19 @@ func TestLFSRender(t *testing.T) {
 		content := doc.Find("div.file-view").Text()
 		assert.Contains(t, content, "Testing READMEs in LFS")
 	})
+
+	// check that an invalid lfs entry defaults to plaintext
+	t.Run("Invalid", func(t *testing.T) {
+		defer tests.PrintCurrentTest(t)()
+
+		req := NewRequest(t, "GET", "/user2/lfs/src/branch/master/invalid")
+		resp := session.MakeRequest(t, req, http.StatusOK)
+
+		doc := NewHTMLParser(t, resp.Body).doc
+
+		content := doc.Find("div.file-view").Text()
+		assert.Contains(t, content, "oid sha256:9d178b5f15046343fd32f451df93acc2bdd9e6373be478b968e4cad6b6647351")
+	})
 }
 
 // TestLFSLockView tests the LFS lock view on settings page of repositories