[wasm] improve handling of malformed input

test/unittests/wasm/loop-assignment-analysis-unittest.cc

Index: test/unittests/wasm/loop-assignment-analysis-unittest.cc
diff --git a/test/unittests/wasm/loop-assignment-analysis-unittest.cc b/test/unittests/wasm/loop-assignment-analysis-unittest.cc
index 7d97c5065e814284f1b956ffbcab0d90b6c22304..c134de890d22ff73bc42944e45c75d1b5613155f 100644
--- a/test/unittests/wasm/loop-assignment-analysis-unittest.cc
+++ b/test/unittests/wasm/loop-assignment-analysis-unittest.cc
@@ -180,6 +180,14 @@ TEST_F(WasmLoopAssignmentAnalyzerTest, Loop2) {
   }
 }
 
+TEST_F(WasmLoopAssignmentAnalyzerTest, Malformed) {
+  byte code[] = {kExprLoop, kExprF32Neg, kExprBrTable, 0x0e, 'h', 'e',
+                 'l',       'l',         'o',          ',',  ' ', 'w',
+                 'o',       'r',         'l',          'd',  '!'};
+  BitVector* assigned = Analyze(code, code + arraysize(code));
+  CHECK_NULL(assigned);
+}
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8