Doing {{}} crashes the program

[PythonCoderAS]

I was just tinkering with JavaScript objects, and I decided to make an object {{}}. This caused the program to crash.

> {{}} 
(node:13519) UnhandledPromiseRejectionWarning: evalmachine.<anonymous>:1
({{}})
  ^

SyntaxError: Unexpected token '{'
    at new Script (vm.js:99:7)
    at Object.<anonymous> (/Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/eval.js:92:24)
    at Generator.next (<anonymous>)
    at /Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/eval.js:7:71
    at new Promise (<anonymous>)
    at __awaiter (/Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/eval.js:3:12)
    at evaluate (/Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/eval.js:90:32)
    at /Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/cli.js:148:47
    at Generator.next (<anonymous>)
    at fulfilled (/Users/example/.npm/_npx/13516/lib/node_modules/jay-repl/dist/cli.js:5:58)
(node:13519) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
(node:13519) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

I tested this in the normal node repl, and it left undefined as expected.

> {{}}
undefined

Related: #24