Default platforms: null in forge config "makers" prevents app from starting

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• [x ] I have searched the issue tracker for a bug that matches the one I want to file, without success.

Issue Details

I am in the process of migrating from electron-forge v5. After running yarn electron-forge import, npm start fails to start the app and outputs the error below.

• Electron Forge Version:
  • 6.0.0-beta.54
• Electron Version:
  • v10.1.5
• Operating System:
  • MacOS 10.15.7
• Last Known Working Electron Forge version::
  • 5.x

Expected Behavior

The electron app should start.

Actual Behavior

An unhandled rejection has occurred inside Forge:
TypeError: Cannot convert undefined or null to object
    at Function.entries (<anonymous>)
    at proxify (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/util/forge-config.ts:23:35)
    at proxify (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/util/forge-config.ts:25:33)
    at proxify (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/util/forge-config.ts:25:33)
    at proxify (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/util/forge-config.ts:25:33)
    at _default (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/util/forge-config.ts:151:10)
    at _default (/Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/core/src/api/start.ts:37:23)
    at /Users/pixelfiend/workspace/LPLMercury/node_modules/@electron-forge/cli/src/electron-forge-start.ts:58:19

Electron Forge was terminated. Location:
{}

To Reproduce

Set platforms: null in and of the forge config's "makers"

module.exports = {
  "packagerConfig": {
    "icon": "./src/assets/icons/logo-green-icon-1024"
  },
  "makers": [
    {
      "name": "@electron-forge/maker-squirrel",
      "platforms": null
    },
  ]
}