Fix some image proxy headers

src/lib/utils/request_backends/node-fetch.js

@@ -10,10 +10,12 @@ class NodeFetch {
 	}
 
 	response() {
-		return this.instance.then(res => ({
+		return this.instance.then(res => {
-			status: res.status,
+			return {
-			headers: new Map(Object.entries(res.headers))
+				status: res.status,
-		}))
+				headers: res.headers
+			}
+		})
 	}
 
 	json() {