Add comprehensive logging to handleImageUpload + fix saveField re-throw

Logging added at every step:
- handleImageUpload entry
- dimPromise resolution
- thumbPromise resolution
- Upload response status + ok flag + url
- r.json() resolution
- selectMediaItem call

Also: saveField now re-throws after logging so callers know save failed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/core/src/visual-editing/toolbar.ts

@@ -731,6 +731,7 @@ export function renderToolbar(config: ToolbarConfig): string {
     .catch(function(err) {
       setSaveState("error");
       console.error("Save failed:", err);
+      throw err;
     });
   }
 
@@ -1149,6 +1150,7 @@ export function renderToolbar(config: ToolbarConfig): string {
   }
 
   function handleImageUpload(file, popover, annotation, element, imgEl) {
+    console.log("[emdash] handleImageUpload called, file:", file.name);
     var collection = annotation.collection;
     var id = annotation.id;
     var field = annotation.field;
@@ -1180,6 +1182,7 @@ export function renderToolbar(config: ToolbarConfig): string {
     });
 
     dimPromise.then(function(dims) {
+      console.log("[emdash] dims resolved:", JSON.stringify(dims));
       // Generate a thumbnail for large images to avoid OOM in server-side
       // blurhash generation on memory-constrained runtimes (Workers).
       // Thumbnail fits within a 64x64 box (scale by max dimension) so that
@@ -1227,6 +1230,7 @@ export function renderToolbar(config: ToolbarConfig): string {
       }
 
       return thumbPromise.then(function(thumbnail) {
+        console.log("[emdash] thumbPromise resolved, thumbnail:", thumbnail ? "yes" : "no");
         var formData = new FormData();
         formData.append("file", file);
         if (dims.width) formData.append("width", String(dims.width));
@@ -1241,8 +1245,7 @@ export function renderToolbar(config: ToolbarConfig): string {
       });
     })
     .then(function(r) {
-      console.log("[emdash] Upload response status:", r.status);
+      console.log("[emdash] Upload response status:", r.status, "ok:", r.ok, "url:", r.url);
-      console.log("[emdash] Upload response headers:", r.headers.get("content-type"));
       if (!r.ok) {
         return r.text().then(function(text) {
           console.log("[emdash] Upload error text:", text);
@@ -1257,9 +1260,12 @@ export function renderToolbar(config: ToolbarConfig): string {
       return r.json();
     })
     .then(function(data) {
+      console.log("[emdash] r.json() resolved, data:", JSON.stringify(data));
       if (!data.data || !data.data.item) throw new Error("Upload failed: no item returned");
       var item = data.data.item;
-      selectMediaItem(item, annotation, element, imgEl);
+      console.log("[emdash] Calling selectMediaItem with item id:", item.id);
+      // Return the saveField promise so rejections propagate to catch
+      return selectMediaItem(item, annotation, element, imgEl);
     })
     .catch(function(err) {
       console.error("Upload error:", err);