Avoid directly calling AddError. (#16275)

src/Compilers/CSharp/Portable/Parser/LanguageParser.cs

@@ -11250,7 +11250,9 @@ private QueryBodySyntax ParseQueryBody()
                         selectOrGroupBy = this.ParseGroupClause();
                         break;
                     default:
-                        selectOrGroupBy = this.AddError(_syntaxFactory.SelectClause(SyntaxFactory.MissingToken(SyntaxKind.SelectKeyword), this.CreateMissingIdentifierName()), ErrorCode.ERR_ExpectedSelectOrGroup);
+                        selectOrGroupBy = _syntaxFactory.SelectClause(
+                            this.EatToken(SyntaxKind.SelectKeyword, ErrorCode.ERR_ExpectedSelectOrGroup),
+                            this.CreateMissingIdentifierName());
                         break;
                 }