fix(nc-gui): revise download attachment logic

packages/nc-gui/components/cell/attachment/utils.ts

@@ -12,6 +12,7 @@ import {
   inject,
   isImage,
   message,
+  mimeTypes,
   ref,
   useApi,
   useAttachment,
@@ -230,21 +231,28 @@ export const [useProvideAttachmentCell, useAttachmentCell] = useInjectionState(
     /** download a file */
     async function downloadFile(item: AttachmentType) {
       const src = getAttachmentSrc(item)
+      const mimeType = mimeTypes[item?.mimetype?.split('/')?.pop() || 'txt']
+      // test if the first source is accessible or not
       await fetch(src)
         .then((res) => {
-          if (!res.ok || res.headers.get('Content-Type') !== item.mimetype) {
+          // if not accessible or the content type doesn't match
+          // then throw the error to trigger the fallback source
+          if (!res.ok || res.headers.get('Content-Type') !== mimeType) {
             throw new Error('Failed to download file')
           }
+          // if accessible, then call blob()
           res.blob()
         })
         .then(async (_) => {
+          // save the file from the first source
           ;(await import('file-saver')).saveAs(src, item.title)
         })
         .catch(async (_) => {
+          // try the fallback source with similar logic
           const fallbackSrc = item.url!
           await fetch(fallbackSrc)
             .then((res) => {
-              if (!res.ok || res.headers.get('Content-Type') !== item.mimetype) {
+              if (!res.ok || res.headers.get('Content-Type') !== mimeType) {
                 throw new Error('Failed to download file')
               }
               res.blob()