I can't use the Document interface in my WarpJS warped function.

var wordElement = document.createElement('ul'); // create single word element

engine-prod.js:30 Uncaught (in promise) 
ReferenceError {stack: "ReferenceError: document is not defined↵    at fn …ndRejections (internal/process/next_tick.js:81:5)", message: "document is not defined"}
stack: "ReferenceError: document is not defined↵    at fn (eval at buildAndEvalEnvironment (/home/stef/dev/heart-of-words/.warp/server-emulation/node_modules/@warpjs/flow-server/flowServer.js:18:20209), <anonymous>:196:23)↵    at fn (eval at buildAndEvalEnvironment (/home/stef/dev/heart-of-words/.warp/server-emulation/node_modules/@warpjs/flow-server/flowServer.js:18:20209), <anonymous>:56:9)↵    at fn (eval at buildAndEvalEnvironment (/home/stef/dev/heart-of-words/.warp/server-emulation/node_modules/@warpjs/flow-server/flowServer.js:18:20209), <anonymous>:9:5)↵    at Flow.flowRun (/home/stef/dev/heart-of-words/.warp/server-emulation/node_modules/@warpjs/flow-server/flowServer.js:18:7073)↵    at processTicksAndRejections (internal/process/next_tick.js:81:5)"
message: "document is not defined"
__proto__: Error

@warpjs/webpack-plugin: ^1.1.0-rc1
@warpjs/engine: ^1.1.0-rc1