title: Flutter: How to implement recaptcha for firebase auth plugin
body: <p>I wanna implement firebase auth method but it want me recaptcha when I pass recaptcha I face to this problem</p>
  <pre><code>E/flutter (19828): [ERROR:flutter/lib/ui/ui_dart_state.cc(177)] Unhandled Exception: NoSuchMethodError: The method 'delegateFor' was called on null.
  E/flutter (19828): Receiver: null
  E/flutter (19828): Tried calling: delegateFor(container: &quot;recptcha&quot;, onError: Closure: (FirebaseAuthException) =&gt; Null, onExpired: Closure: () =&gt; void, onSuccess: Closure: () =&gt; void, size: Instance of 'RecaptchaVerifierSize', theme: Instance of 'RecaptchaVerifierTheme')
  </code></pre>
  <p>Here is my code :</p>
  <pre><code>FirebaseAuth.instance.signInWithPhoneNumber(
    phoneNumber,
    RecaptchaVerifier(
      container: 'recptcha',
      onError: (e) {
        print(e);
      },
      onExpired: () =&gt; print(&quot;Expired&quot;),
      onSuccess: () =&gt; print(&quot;Success&quot;),
      size: RecaptchaVerifierSize.compact,
      theme: RecaptchaVerifierTheme.light,
    ),
  );
  </code></pre>