fix #2599 (segmentation fault of cppcheck ( sizeof ))

lib/tokenize.cpp

@@ -3809,6 +3809,9 @@ void Tokenizer::simplifySizeof()
         if (tok->str() != "sizeof")
             continue;
 
+        if (!tok->next())
+            break;
+
         if (Token::simpleMatch(tok->next(), "sizeof"))
             continue;
 

test/testsimplifytokens.cpp

@@ -84,6 +84,7 @@ private:
         TEST_CASE(sizeof19);    // #1891 - sizeof 'x'
         TEST_CASE(sizeof20);    // #2024 - sizeof a)
         TEST_CASE(sizeof21);    // #2232 - sizeof...(Args)
+        TEST_CASE(sizeof22);    // #2599
         TEST_CASE(sizeofsizeof);
         TEST_CASE(casting);
 
@@ -1418,6 +1419,15 @@ private:
         tok(code);
     }
 
+    void sizeof22()
+    {
+        // ticket #2599 segmentation fault
+        const char code[] = "sizeof\n";
+
+        // don't segfault
+        tok(code);
+    }
+
 
     void sizeofsizeof()
     {