feat: Remove script element immediately in injectScript

Everything seems to work: the script is executed; onload, onerror
handlers do the right thing; document.currentScript invoked by the
script returns the detached script element.

Author: ion1

packages/wxt/src/utils/inject-script.ts

@@ -32,11 +32,11 @@ export async function injectScript(
     script.src = url;
   }
 
+  (document.head ?? document.documentElement).append(script);
+
   if (!options?.keepInDom) {
-    script.onload = () => script.remove();
+    script.remove();
   }
-
-  (document.head ?? document.documentElement).append(script);
 }
 
 export interface InjectScriptOptions {