AK: Fix JSON parser crashing when encountering UTF-8

The mechanism that caches the most recently seen string for each first
character was indexing into the cache using a 'char' subscript. Oops!

1 files changed, 8 insertions, 0 deletions

diff --git a/AK/Tests/TestJSON.cpp b/AK/Tests/TestJSON.cpp
index bbdfd25817..e532040c4d 100644
--- a/AK/Tests/TestJSON.cpp
+++ b/AK/Tests/TestJSON.cpp
@@ -74,4 +74,12 @@ TEST_CASE(json_empty_string)
     EXPECT_EQ(json.as_string().is_empty(), true);
 }
 
+TEST_CASE(json_utf8_character)
+{
+    auto json = JsonValue::from_string("\"\xc3\x84\"");
+    EXPECT_EQ(json.type(), JsonValue::Type::String);
+    EXPECT_EQ(json.as_string().is_null(), false);
+    EXPECT_EQ(json.as_string().length(), 2);
+}
+
 TEST_MAIN(JSON)