diff --git a/doc/images/scanner.png b/doc/images/scanner.png
new file mode 100644
index 000000000..9c39ef0a5
Binary files /dev/null and b/doc/images/scanner.png differ
diff --git a/doc/json.gif b/doc/json.gif
index 62a1a2eb9..cc2a9726d 100644
Binary files a/doc/json.gif and b/doc/json.gif differ
diff --git a/test/src/unit-deserialization.cpp b/test/src/unit-deserialization.cpp
index 9de25f97c..01441b1af 100644
--- a/test/src/unit-deserialization.cpp
+++ b/test/src/unit-deserialization.cpp
@@ -223,5 +223,21 @@ TEST_CASE("deserialization")
                 CHECK_THROWS_AS(json::parse(std::begin(v), std::end(v)), std::invalid_argument);
             }
         }
+
+        // these cases are required for 100% line coverage
+        SECTION("error cases")
+        {
+            SECTION("case 1")
+            {
+                uint8_t v[] = {'\"', 'a', 'a', 'a', 'a', 'a', 'a', '\\', 'u'};
+                CHECK_THROWS_AS(json::parse(std::begin(v), std::end(v)), std::invalid_argument);
+            }
+
+            SECTION("case 2")
+            {
+                uint8_t v[] = {'\"', 'a', 'a', 'a', 'a', 'a', 'a', '\\', 'u', '1'};
+                CHECK_THROWS_AS(json::parse(std::begin(v), std::end(v)), std::invalid_argument);
+            }
+        }
     }
 }