fix: download button main channel versions

Author: MiniDigger

frontend/src/components/projects/DownloadButton.vue

@@ -173,7 +173,7 @@ function formatVersionRange(versions: string[]): string {
       </DropdownItem>
     </DropdownButton>
 
-    <DropdownButton v-else-if="project.mainChannelVersions?.length" :button-size="small ? 'medium' : 'large'">
+    <DropdownButton v-else-if="project.mainChannelVersions && Object.keys(project.mainChannelVersions).length > 0" :button-size="small ? 'medium' : 'large'">
       <template #button-label>
         <span class="items-center inline-flex">
           <IconMdiDownloadOutline />