More information to my previous comment. I opened developer tools and then clicked start and got the following:
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Loaded state from IndexedDB storage (113186 bytes)
734 c2runtime.js:2 Uncaught TypeError: Cannot read property 'type' of null
at g.g_oX (c2runtime.js:2)
at g.g_oN (c2runtime.js:2)
at g.g_lK (c2runtime.js:2)
at g.g_lz (c2runtime.js:2)
at g.g_iT (c2runtime.js:2)
at g_iS (c2runtime.js:2)
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The number (734) endlessly increments.
 "Idle Squares 2"){kind=icon}