fix(ui): prevent NaN aspect ratio in createThumbnail on svg files (#10488)

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Fixes #

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### What?
This PR fixes an issue for Firefox users encountered when
drag-and-dropping an svg file into the BulkUpload drawer dropzone where,
because of both img.width and img.height being 0, aspect ratio becomes
NaN due to division by zero.

### Why?
To prevent a runtime error for Firefox users and to render an
appropriate thumbnail as expected.

### How?
By logically checking that the divisor, in this case `img.height` is not
zero, and setting a fallback if so.

Notes:
- This is a follow-up to an issue I found while authoring #10475 which
shows up as a runtime error in the below videos as well.
- As a result of this PR, I was reminded of another bug where thumbnails
were not correctly updated if the BulkUpload EditForm contained only
some successful files saved.

Before:

https://github.com/user-attachments/assets/e1b12a55-551a-4fcb-9df7-dabde87729b6

After:

https://github.com/user-attachments/assets/52791919-b657-4580-ac37-ca4be749c9a7

---------

Co-authored-by: Paul Popus <paul@payloadcms.com>

Author: akhrarovsaid

packages/ui/src/elements/BulkUpload/FormsManager/index.tsx

@@ -164,7 +164,7 @@ export function FormsManagerProvider({ children }: FormsManagerProps) {
         'Accept-Language': i18n.language,
         'Content-Type': 'application/json',
       },
-      method: 'post',
+      method: 'POST',
     })
 
     const json: SanitizedDocumentPermissions = await res.json()

packages/ui/src/elements/Thumbnail/createThumbnail.ts

@@ -11,7 +11,7 @@ export const createThumbnail = (file: File): Promise<string> => {
       let drawHeight: number, drawWidth: number
 
       // Calculate aspect ratio
-      const aspectRatio = img.width / img.height
+      const aspectRatio = img.height && img.width ? img.width / img.height : 1
 
       // Determine dimensions to fit within maxDimension while maintaining aspect ratio
       if (aspectRatio > 1) {