Uncaught (in promise) Error: Unknown public property "is:true" of element <lightning-layout-item>. This is likely a typo on the corresponding attribute "is:true".

[tgentet-obrien]

Describe the bug I developed an LWC in my org, which works perfectly fine! However, when I Start the local dev server and go to my LWC to load it, I get the following error in the JS Console: Uncaught (in promise) Error: Unknown public property "is:true" of element <lightning-layout-item>. This is likely a typo on the corresponding attribute "is:true".

To Reproduce Steps to reproduce the behavior:

1. Create an LWC with just just 1 element and add the is:true attribute to it
2. Start the Local Dev Server
3. Go to your LWC with the is:true attribute

Expected behavior The LWC loads without an error

Screenshots

Desktop (please complete the following information):

• OS: macOS Catalina v10.15.6
• Browser: Chrome
• Version: 86.0.4240.193 (Official Build) (x86_64)

Additional context Add any other context about the problem here.

[stale[bot]]

This issue has been automatically marked as type:bug-p3 because it has not had recent activity.

[git2gus[bot]]

This issue has been linked to a new work item: W-8484294

[JackVeromeev]

@tgentet-obrien, this is a typo. LWC supports if:true and if:false flags in order to render/skip the components. Suppose you can close it.

[tgentet-obrien]

@JackVeromeev it's not that, the if true and false attributes are working find in Salesforce, it was only when running the LWC locally that it threw an error

[JackVeromeev]

@tgentet-obrien but in the initial issue you pasted the stacktrace with is:true instead of if:true

[stale[bot]]

This issue has been automatically marked as type:bug-p3 because it has not had recent activity.