Storybook 6.3.7 start-storybook: TypeError: (tag.text || "").trim is not a function

[jimsheen]

Describe the bug
After upgrading to Storybook 6.3.7 (6.3.6 had same issue too) I am receiving this error:

TypeError: (tag.text || "").trim is not a function
    at /node_modules/react-docgen-typescript-loader/node_modules/react-docgen-typescript/lib/parser.js:475:48

To Reproduce
Install storybook and add reactDocgen: 'react-docgen-typescript', to the config in main.js

  check: false,
  checkOptions: {
    silent: true
  },
  reactDocgen: 'react-docgen-typescript',
  reactDocgenTypescriptOptions: {
    shouldExtractLiteralValuesFromEnum: true,
    shouldExtractValuesFromUnion: true,
    // compilerOptions: {
    //   allowSyntheticDefaultImports: true,
    //   esModuleInterop: true
    // },
    shouldRemoveUndefinedFromOptional: true,
    propFilter: (prop) => (prop.parent ? !/node_modules/.test(prop.parent.fileName) : true),
  },
}```

[shilman]

closing as dupe to #15067