Add null pointer check to fix SEGFAULT (#1499)

* Add null pointer check to fix segfault

* Add first test case to reproduce problem

Author: knowledge4igor

lib/valueflow.cpp

@@ -2964,7 +2964,7 @@ static void valueFlowAfterMove(TokenList *tokenlist, SymbolDatabase* symboldatab
                 (parent->str() == "return" || // MOVED in return statement
                  parent->str() == "(")) // MOVED in self assignment, isOpenParenthesisMemberFunctionCallOfVarId == true
                 continue;
-            if (parent && parent->astOperand1()->varId() == varId)
+            if (parent && parent->astOperand1() && parent->astOperand1()->varId() == varId)
                 continue;
             const Variable *var = varTok->variable();
             if (!var)

test/testvalueflow.cpp

@@ -495,6 +495,20 @@ class TestValueFlow : public TestFixture {
                "    return h(std::move(x));\n"
                "}";
         ASSERT_EQUALS(false, testValueOfX(code, 5U, ValueFlow::Value::MovedVariable));
+
+        code = "struct X {\n"
+               "};\n"
+               "struct Data {\n"
+               "  template<typename Fun>\n"
+               "  void foo(Fun f) {}\n"
+               "};\n"
+               "Data g(X value) { return Data(); }\n"
+               "void f() {\n"
+               "   X x;\n"
+               "   g(std::move(x)).foo([=](int value) mutable {;});\n"
+               "   X y=x;\n"
+               "}";
+        TODO_ASSERT_EQUALS(true, false, testValueOfX(code, 11U, ValueFlow::Value::MovedVariable));
     }
 
     void valueFlowCalculations() {