Assertion failed: Expected variable declaration as init part of a for-in loop, found Identifier

node parser.js ../../Protobuf/ast.proto code.js output.ast.proto

code.js:

for (x in y) {}

Tested on rev d386a838.

<repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:17
            throw "Assertion failed: " + msg;
            ^
Assertion failed: Expected variable declaration as init part of a for-in loop, found Identifier
Thrown at:
    at assert (<repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:17:13)
    at visitStatement (<repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:268:17)
    at visitProgram (<repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:51:37)
    at parse (<repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:561:12)
    at <repo>/Sources/Fuzzilli/Compiler/Parser/parser.js:570:15
    at finish (<repo>/Sources/Fuzzilli/Compiler/Parser/node_modules/protobufjs/src/root.js:105:9)
    at process (<repo>/Sources/Fuzzilli/Compiler/Parser/node_modules/protobufjs/src/root.js:143:13)
    at <repo>/Sources/Fuzzilli/Compiler/Parser/node_modules/protobufjs/src/root.js:195:17
    at fetchReadFileCallback (<repo>/Sources/Fuzzilli/Compiler/Parser/node_modules/@protobufjs/fetch/index.js:51:19)
    at readFileAfterClose (node:internal/fs/read/context:68:3)

Start in Sources/Fuzzilli/Compiler/Parser/parser.js, especially visitStatement around line 268, and reproduce the failure with code.js containing for (x in y) {}. Confirm that the parser accepts this for-in form without the assertion, using the command shown in the issue; no test file is named.