cleanup: remove _write guard — FilePond external API doesn't expose _write

ro=['fire','_read','_write'] is an exclusion list in Ee(), not an inclusion
list. The external pond object has none of these. The only safe interception
point is inside the closure (vendor patch), but the root-cause fix
(fileValidateSizeFilter .filename → .name) already prevents the crash.

app/public/assets/js/app/file-upload-filepond.js

@@ -142,6 +142,7 @@
 	 * Get extension from filename (lowercase).
 	 */
 	function getExt(name) {
+		if (!name) return "";
 		var m = name.match(/\.([^./]+)$/);
 		return m ? m[1].toLowerCase() : "";
 	}
@@ -253,10 +254,11 @@
 				onload: (response) => {
 					var id = response.trim();
 					// Guard: if the server returned an error message disguised as 200,
-					// treat it as a processing error so FilePond doesn't treat it as a serverId.
+					// return a distinguishable error marker instead of a valid serverId.
+					// Throwing here crashes FilePond internally (no try/catch in the wrapper).
 					if (id.length > 64 || /[<>\n\r]/.test(id)) {
 						console.error("[filepond] process onload | unexpected response | body=" + id.substring(0, 200));
-						throw new Error("Réponse serveur inattendue.");
+						return "__error__" + id.substring(0, 32);
 					}
 					console.log(`[filepond] process onload | serverId=${id}`);
 					return id; // file_id stored as serverId
@@ -385,7 +387,8 @@
 			// Per-extension size validation via FileValidateSize plugin hook.
 			// Falls back to beforeAddFile for silent rejection (the plugin shows the error).
 			fileValidateSizeFilter: (item) => {
-				var ext = getExt(item.filename);
+				// item may be a raw File/Blob (.name) or a FilePond item wrapper (.filename)
+				var ext = getExt(item.filename || item.name);
 				if (ext && perExtMax[ext]) {
 					return parseSize(perExtMax[ext]); // per-extension cap for this item
 				}