fix: avoid hiding remote lookup errors

lib/nextcloud.ts

@@ -63,12 +63,13 @@ async function davRequest(
 
 /** Check if a folder exists on the Nextcloud instance. */
 export async function folderExists(path: string): Promise<boolean> {
-  try {
-    const res = await davRequest('PROPFIND', path + '/', null, { Depth: '0' })
-    return res.status >= 200 && res.status < 300
-  } catch {
-    return false
-  }
+  const res = await davRequest('PROPFIND', path + '/', null, { Depth: '0' })
+
+  if (res.status === 404) return false
+  if (res.status >= 200 && res.status < 300) return true
+
+  const text = await res.text().catch(() => '')
+  throw new Error(`PROPFIND ${path} failed (${res.status}): ${text.slice(0, 200)}`)
 }
 
 /**