From 2198e5088a592843e18f0f1e536b7b2e215739f4 Mon Sep 17 00:00:00 2001
From: Trevor Manz <trevor.j.manz@gmail.com>
Date: Tue, 14 Nov 2023 14:20:27 -0500
Subject: [PATCH] fix(loaders): Allow optional TiffData in OME-XML (#714)

---
 CHANGELOG.md                   |  1 +
 packages/loaders/src/omexml.ts |  2 +-
 sites/avivator/src/utils.js    | 16 +++++++++++++++-
 3 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1f6491f76..4971f7e58 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 
 ### Changed
 - Fix Avivator demo for OME-Zarr with only spatial axes
+- Allow OME-XML to omit `TiffData` tags
 
 ## 0.14.1
 
diff --git a/packages/loaders/src/omexml.ts b/packages/loaders/src/omexml.ts
index f3edf62d5..00c034af0 100644
--- a/packages/loaders/src/omexml.ts
+++ b/packages/loaders/src/omexml.ts
@@ -114,7 +114,7 @@ const TiffDataSchema = z
 const PixelsSchema = z
   .object({
     Channel: z.preprocess(ensureArray, ChannelSchema.array()),
-    TiffData: z.preprocess(ensureArray, TiffDataSchema.array())
+    TiffData: z.preprocess(ensureArray, TiffDataSchema.array()).optional()
   })
   .extend({
     attr: z.object({
diff --git a/sites/avivator/src/utils.js b/sites/avivator/src/utils.js
index cec9b5d13..a41e04cb1 100644
--- a/sites/avivator/src/utils.js
+++ b/sites/avivator/src/utils.js
@@ -135,6 +135,14 @@ async function getTotalImageCount(src, rootMeta, data) {
   return numImagesPerResolution * levels;
 }
 
+/**
+ * @param {unknown} e
+ * @returns {e is Error & { issues: unknown }}
+ */
+function isZodError(e) {
+  return e instanceof Error && 'issues' in e;
+}
+
 /**
  * Given an image source, creates a PixelSource[] and returns XML-meta
  *
@@ -211,7 +219,13 @@ export async function createLoader(
     let source;
     try {
       source = await loadBioformatsZarr(urlOrFile);
-    } catch {
+    } catch (e) {
+      if (isZodError(e)) {
+        // If the error is a ZodError, it means there was an OME-XML file
+        // but it was invalid. We shouldn't try to load the file as a OME-Zarr.
+        throw e;
+      }
+
       // try ome-zarr
       const res = await loadOmeZarr(urlOrFile, { type: 'multiscales' });
       // extract metadata into OME-XML-like form