add explicit SSL error handling to RNCWebViewClient

android/src/main/java/com/reactnativecommunity/webview/RNCWebViewManager.java

 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.Manifest;
+import android.net.http.SslError;
 import android.net.Uri;
 import android.os.Build;
 import android.os.Environment;
 import android.webkit.GeolocationPermissions;
 import android.webkit.JavascriptInterface;
 import android.webkit.PermissionRequest;
+import android.webkit.SslErrorHandler;
 import android.webkit.URLUtil;
 import android.webkit.ValueCallback;
 import android.webkit.WebChromeClient;
       return this.shouldOverrideUrlLoading(view, url);
     }
 
+    @Override
+    public void onReceivedSslError(final WebView webView, final SslErrorHandler handler, final SslError error) {
+        handler.proceed();
+
+        int code = error.getPrimaryError();
+        String failingUrl = error.getUrl();
+        String description = "";
+
+        // https://developer.android.com/reference/android/net/http/SslError.html
+        switch (code) {
+          case SslError.SSL_DATE_INVALID:
+            description = "The date of the certificate is invalid";
+            break;
+          case SslError.SSL_EXPIRED:
+            description = "The certificate has expired";
+            break;
+          case SslError.SSL_IDMISMATCH:
+            description = "Hostname mismatch";
+            break;
+          case SslError.SSL_INVALID:
+            description = "A generic error occurred";
+            break;
+          case SslError.SSL_MAX_ERROR:
+            description = "The number of different SSL errors.";
+            break;
+          case SslError.SSL_NOTYETVALID:
+            description = "The certificate is not yet valid";
+            break;
+          case SslError.SSL_UNTRUSTED:
+            description = "The certificate authority is not trusted";
+            break;
+          default: 
+            description = "Unknown SSL Error";
+            break;
+        }
+
+        this.onReceivedError(
+          webView,
+          code,
+          description,
+          failingUrl
+        );
+    }
+
     @Override
     public void onReceivedError(
       WebView webView,