fix md file uploading problem

web/app/components/base/file-uploader/utils.ts

@@ -42,11 +42,21 @@ export const fileUpload: FileUpload = ({
     })
 }
 
+const additionalExtensionMap = new Map<string, string[]>([
+  ['text/x-markdown', ['md']],
+])
+
 export const getFileExtension = (fileName: string, fileMimetype: string, isRemote?: boolean) => {
   let extension = ''
   let extensions = new Set<string>()
-  if (fileMimetype)
-    extensions = mime.getAllExtensions(fileMimetype) || new Set<string>()
+  if (fileMimetype) {
+    const extensionsFromMimeType = mime.getAllExtensions(fileMimetype) || new Set<string>()
+    const additionalExtensions = additionalExtensionMap.get(fileMimetype) || []
+    extensions = new Set<string>([
+      ...extensionsFromMimeType,
+      ...additionalExtensions,
+    ])
+  }
 
   let extensionInFileName = ''
   if (fileName) {