Fix issues with Openverse image names

See #693

packages/upload-media/src/store/private-actions.ts

@@ -21,6 +21,7 @@ import { UploadError } from '../upload-error';
 import {
 	canProcessWithFFmpeg,
 	cloneFile,
+	convertBlobToFile,
 	fetchFile,
 	getFileBasename,
 	getFileExtension,
@@ -153,7 +154,8 @@ type ThunkArgs = {
 };
 
 interface AddItemArgs {
-	file: File;
+	// It should always be a File, but some consumers might still pass Blobs only.
+	file: File | Blob;
 	batchId?: BatchId;
 	onChange?: OnChangeHandler;
 	onSuccess?: OnSuccessHandler;
@@ -183,7 +185,7 @@ interface AddItemArgs {
  * @param [$0.operations]         List of operations to perform. Defaults to automatically determined list, based on the file.
  */
 export function addItem( {
-	file,
+	file: fileOrBlob,
 	batchId,
 	onChange,
 	onSuccess,
@@ -202,6 +204,10 @@ export function addItem( {
 
 		const itemId = uuidv4();
 
+		// Hardening in case a Blob is passed instead of a File.
+		// See https://github.com/WordPress/gutenberg/pull/65693 for an example.
+		const file = convertBlobToFile( fileOrBlob );
+
 		let blobUrl;
 
 		// StubFile could be coming from addItemFromUrl().

packages/upload-media/src/utils.ts

@@ -18,6 +18,31 @@ import {
 } from './constants';
 import { UploadError } from './upload-error';
 
+/**
+ * Converts a Blob to a File with a default name like "image.png".
+ *
+ * If it is already a File object, it is returned unchanged.
+ *
+ * @param fileOrBlob Blob object.
+ * @return File object.
+ */
+export function convertBlobToFile( fileOrBlob: Blob | File ): File {
+	if ( fileOrBlob instanceof File ) {
+		return fileOrBlob;
+	}
+
+	// Extension is only an approximation.
+	// The server will override it if incorrect.
+	const ext = fileOrBlob.type.split( '/' )[ 1 ];
+	const mediaType =
+		'application/pdf' == fileOrBlob.type
+			? 'document'
+			: fileOrBlob.type.split( '/' )[ 0 ];
+	return new File( [ fileOrBlob ], `${ mediaType }.${ ext }`, {
+		type: fileOrBlob.type,
+	} );
+}
+
 /**
  * Renames a given file and returns a new file.
  *