Chrome extension fails to load when I add icons - google-chrome-extension

Question

I've been learning how to make a Chrome extension and have been stuck on just adding an icon for a while now, I've copy pasted code that supposedly works but I keep getting this error:
Could not load icon 'icon16.png' specified in 'icons'.
Could not load manifest.
My code:
{
"manifest_version": 3,
"name": "extension",
"description": "test",
"version": "1.0",
"browser_action": {
"default_icon": "icon48.png"
},
"icons": {
"16": "icon16.png",
"48": "icon48.png",
"128": "icon128.png"
},
"content_scripts": [
{
"js": [
"test.js"
],
"matches": [
"https://www.test.com/*"
]
}
]
}
I've triple checked that every image is in fact a PNG and is of the right size. I have a single directory with manifest.json, test.js, and all three images (as well as a.prettierrc file, although I doubt that has any impact).
If I remove the icons part of manifest.json the extension works perfectly.

Answer 1

The error about not being able to load the manifest is likely related to:
"browser_action": {
"default_icon": "icon48.png"
},
which is from Manifest Version 2. The "browser_action" field should be changed to:
"action": {
"default_icon": "icon48.png"
},
For further reference see here: Action API unification