I implemented a long press click event using Mouse Up and Mouse Down events, making use of a state variable and performance.now() JS function.
It works quite well but now I am held hostage by the page data state variables section which no longer allows me to delete or rename state variables (screenshot).
This happens regardless of whether I am using performance.now() or window.performance.now()
Earlier today, I was also getting these errors while using setTimeout and clearTimeout functions.
Looks like the only way to restore state variables delete and rename functionality is by deleting the code or the actions mentioned in the error. Not very convenient, because the code works.
Note this error displays twice - when attempting to delete or rename a state variable and then again when clicking outside the right sidebar onto the arena canvas OR when mousing over the page canvas
Oh, on top of not being able to rename and delete variables, I can’t even rename any components anymore
Ok, forget renaming components, I cannot change any values for anything anymore! 
Trying to change the size or font of some static text does nothing with no errors displayed.
Originally, I used window.performance.now() in the event actions. Then, I changed it to just performance.now() and it still worked.
After refreshing the project page, I got errors about performance.now() not being defined, so I changed it back to window.performance.now().
Note the undefined errors did not show until I refreshed the page, so there is something odd happening with the way the code expressions are parsed/checked.
Looking into this issue now.
Quick note to confirm that these issues have been solved. @icaro and the Plasmic team were quick to deploy a fix. Cheers! 