[clang-format] Fix crashes due to missing l_paren

[owenpan]

Summary

Fixes https://github.com/llvm/llvm-project/issues/54384.

clang/lib/Format/TokenAnnotator.cpp

case tok::kw_for:
           break;
         // JS' for await ( ...
         if (CurrentToken && CurrentToken->is(Keywords.kw_await))
           next();
       }
       if (Style.isCpp() && CurrentToken && CurrentToken->is(tok::kw_co_await))
         next();
       Contexts.back().ColonIsForRangeExpr = true;
+      if (!CurrentToken || CurrentToken->isNot(tok::l_paren))
+        return false;
       next();
       if (!parseParens())
         return false;
       break;
     case tok::l_paren:
       // When faced with 'operator()()', the kw_operator handler incorrectly
       // marks the first l_paren as a OverloadedOperatorLParen. Here, we make
       // the first two parens OverloadedOperators and the second l_paren an

clang/unittests/Format/FormatTest.cpp

verifyFormat("do {\n"
                "  f();\n"
                "}");
 }
 
 TEST_F(FormatTest, IncorrectCodeMissingParens) {
   verifyFormat("if {\n  foo;\n  foo();\n}");
   verifyFormat("switch {\n  foo;\n  foo();\n}");
   verifyIncompleteFormat("for {\n  foo;\n  foo();\n}");
+  verifyIncompleteFormat("ERROR: for target;");
   verifyFormat("while {\n  foo;\n  foo();\n}");
   verifyFormat("do {\n  foo;\n  foo();\n} while;");
 }
 
 TEST_F(FormatTest, DoesNotTouchUnwrappedLinesWithErrors) {
   verifyIncompleteFormat("namespace {\n"
                          "class Foo { Foo (\n"
                          "};\n"