[wasm] improve handling of malformed input

test/unittests/wasm/leb-helper-unittest.cc

Index: test/unittests/wasm/leb-helper-unittest.cc
diff --git a/test/unittests/wasm/leb-helper-unittest.cc b/test/unittests/wasm/leb-helper-unittest.cc
index ed9f0a325d20b06ef73f26ea6defd8b30fdbaf79..27b3b486f35ccf46a4ada7abd8010d1d123511c9 100644
--- a/test/unittests/wasm/leb-helper-unittest.cc
+++ b/test/unittests/wasm/leb-helper-unittest.cc
@@ -96,7 +96,7 @@ TEST_F(LEBHelperTest, sizeof_i32v) {
     EXPECT_EQ(LEBHelper::sizeof_##name(val),                               \
               static_cast<size_t>(ptr - buffer));                          \
     Decoder decoder(buffer, buffer + kSize);                               \
-    int length = 0;                                                        \
+    unsigned int length = 0;                                               \
     ctype result = decoder.checked_read_##name(buffer, 0, &length);        \
     EXPECT_EQ(val, result);                                                \
     EXPECT_EQ(LEBHelper::sizeof_##name(val), static_cast<size_t>(length)); \