Fix #13123/13124 fuzzing crashes (danmar#6909)

Author: chrchr-github

lib/tokenize.cpp

@@ -8530,6 +8530,9 @@ void Tokenizer::findGarbageCode() const
         else if (Token::Match(tok, "[({<] %assign%"))
             syntaxError(tok);
 
+        else if (Token::Match(tok, "%assign% >"))
+            syntaxError(tok);
+
         else if (Token::Match(tok, "[`\\@]"))
             syntaxError(tok);
 

lib/tokenlist.cpp

@@ -1885,6 +1885,10 @@ void TokenList::validateAst(bool print) const
                 throw InternalError(tok, "Syntax Error: AST broken, binary operator '" + tok->str() + "' doesn't have two operands.", InternalError::AST);
         }
 
+        if (Token::Match(tok, "++|--") && !tok->astOperand1()) {
+            throw InternalError(tok, "Syntax Error: AST broken, operator '" + tok->str() + "' doesn't have an operand.", InternalError::AST);
+        }
+
         // Check control blocks and asserts
         if (Token::Match(tok->previous(), "if|while|for|switch|assert|ASSERT (")) {
             if (!tok->astOperand1() || !tok->astOperand2())

test/cli/fuzz-crash/crash-522f048722bf5f33fa10a32a4c5253d1dc8b01d5

@@ -0,0 +1 @@
+C(){o y=>::*}

test/cli/fuzz-crash/crash-78bcf47420424bf607f6697cf84ddd84b4dfbeb9

@@ -0,0 +1 @@
+assert(a~--)

test/testpostfixoperator.cpp

@@ -305,9 +305,9 @@ class TestPostfixOperator : public TestFixture {
     }
 
     void test2168() {
-        check("--> declare allocator lock here\n"
-              "int main(){}");
-        ASSERT_EQUALS("", errout_str());
+        ASSERT_THROW_INTERNAL(check("--> declare allocator lock here\n"
+                                    "int main(){}"),
+                              AST);
     }
 
     void pointerSimplest() {