gatsby-remark-images only allows loading: lazy

[MelleNi]

Description

When attempting to run a gatsby develop environment with gatsby-remark-images with the option loading set to anything but lazy results in ReferenceError: eager is not defined or ReferenceError: auto is not defined.

Steps to reproduce

Include the option loading: auto, or loading: eager, in gatsby-remark-images

Expected result

It should start the develop environment without errors and enable either of those options for the plugin.

Actual result

An error breaks the process

Environment

System:
OS: macOS 10.15.6
CPU: (16) x64 Intel(R) Core(TM) i9-9880H CPU @ 2.30GHz
Shell: 5.7.1 - /bin/zsh
Binaries:
Node: 12.19.0 - ~/.nvm/versions/node/v12.19.0/bin/node
npm: 6.14.8 - ~/.nvm/versions/node/v12.19.0/bin/npm
Languages:
Python: 3.8.5 - /Users/melle/.pyenv/shims/python
Browsers:
Chrome: 86.0.4240.183
Edge: 86.0.622.43
Firefox: 82.0.2
Safari: 13.1.2
npmPackages:
gatsby: ^2.24.85 => 2.24.85
gatsby-image: ^2.4.21 => 2.4.21
gatsby-plugin-feed: ^2.5.19 => 2.5.19
gatsby-plugin-google-analytics: ^2.3.19 => 2.3.19
gatsby-plugin-manifest: ^2.4.35 => 2.4.35
gatsby-plugin-offline: ^3.2.37 => 3.2.37
gatsby-plugin-percy: ^0.1.4 => 0.1.4
gatsby-plugin-purgecss: ^5.0.0 => 5.0.0
gatsby-plugin-react-helmet: ^3.3.14 => 3.3.14
gatsby-plugin-sharp: ^2.6.43 => 2.6.43
gatsby-remark-copy-linked-files: ^2.3.19 => 2.3.19
gatsby-remark-images: ^3.4.1 => 3.4.1
gatsby-remark-prismjs: ^3.5.16 => 3.5.16
gatsby-remark-responsive-iframe: ^2.4.17 => 2.4.17
gatsby-remark-smartypants: ^2.3.13 => 2.3.13
gatsby-source-filesystem: ^2.3.35 => 2.3.35
gatsby-transformer-remark: ^2.8.46 => 2.8.46
gatsby-transformer-sharp: ^2.5.19 => 2.5.19
npmGlobalPackages:
gatsby-cli: 2.12.114

[sidharthachatterjee]

Based on the error, it appears you're trying to set loading to a variable name? That ought to be loading: "eager"

[MelleNi]

Based on the error, it appears you're trying to set loading to a variable name? That ought to be loading: "eager"

Makes sense, wasn't clear from the documentation. Any idea why lazy without quotes does not return the same error, in that case?