From 30921031653799519a7acab46f5c7da2f81c25d5 Mon Sep 17 00:00:00 2001
From: Dimitris Dafnis <68849116+jim-daf@users.noreply.github.com>
Date: Tue, 21 Apr 2026 21:55:20 +0200
Subject: [PATCH] fix(WebViewClientDelegate): supply non-null favicon
 placeholder to delegates (#490)

Resolves #490

WebView delivers onPageStarted with a null favicon during early page-start.
WebViewClientDelegate forwards that value straight to the user's delegate.
Kotlin delegates whose signature declares the favicon parameter as a
non-null Bitmap (the default in Kotlin source unless explicitly Bitmap?)
crash at the synthetic Intrinsics.checkParameterIsNotNull bytecode:

    Parameter specified as non-null is null:
      method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull,
      parameter favicon

This change substitutes a 1x1 transparent ARGB_8888 placeholder bitmap for
a null favicon before forwarding to the delegate. The placeholder is
lazily created and cached, so there is no cost on the common path where
the platform supplies a real bitmap. Delegates that declared the
parameter as Bitmap? still work, just with a non-null value.
---
 .../just/agentweb/WebViewClientDelegate.java  | 34 +++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/agentweb-core/src/main/java/com/just/agentweb/WebViewClientDelegate.java b/agentweb-core/src/main/java/com/just/agentweb/WebViewClientDelegate.java
index 2b2ed1dd..34526aea 100644
--- a/agentweb-core/src/main/java/com/just/agentweb/WebViewClientDelegate.java
+++ b/agentweb-core/src/main/java/com/just/agentweb/WebViewClientDelegate.java
@@ -68,13 +68,43 @@ public boolean shouldOverrideUrlLoading(WebView view, WebResourceRequest request
         return super.shouldOverrideUrlLoading(view, request);
     }
 
+    /**
+     * One-pixel transparent placeholder used in place of a null favicon when
+     * forwarding {@link #onPageStarted(WebView, String, Bitmap)} to a delegate
+     * whose Kotlin signature declares favicon as a non-null {@code Bitmap}.
+     * Allocated lazily so there is no cost when the platform supplies a real
+     * favicon. See issue #490.
+     */
+    private static volatile Bitmap sFaviconPlaceholder;
+
+    private static Bitmap faviconPlaceholder() {
+        Bitmap placeholder = sFaviconPlaceholder;
+        if (placeholder == null) {
+            synchronized (WebViewClientDelegate.class) {
+                placeholder = sFaviconPlaceholder;
+                if (placeholder == null) {
+                    placeholder = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888);
+                    sFaviconPlaceholder = placeholder;
+                }
+            }
+        }
+        return placeholder;
+    }
+
     @Override
     public void onPageStarted(WebView view, String url, Bitmap favicon) {
+        // Issue #490: WebView may deliver a null favicon at page-start. Kotlin
+        // delegates whose signature declares favicon as non-null Bitmap will
+        // crash at the synthetic Intrinsics.checkParameterIsNotNull check.
+        // Substitute a tiny transparent placeholder so non-null Kotlin
+        // signatures keep working; nullable signatures see no observable
+        // change beyond receiving a non-null bitmap.
+        Bitmap safeFavicon = favicon != null ? favicon : faviconPlaceholder();
         if (mDelegate != null) {
-            mDelegate.onPageStarted(view, url, favicon);
+            mDelegate.onPageStarted(view, url, safeFavicon);
             return;
         }
-        super.onPageStarted(view, url, favicon);
+        super.onPageStarted(view, url, safeFavicon);
     }
 
     @Override