Beni Cherniavsky-Paskin

Reproduced & reported upstream: https://github.com/codemirror/CodeMirror/issues/3510 (why did I wait? was that so hard? maybe I wanted to fix it myself — not sure when I'll get to it but anyway...

There are 2 histories involved: browser's global history of everything you've ever visited (Ctrl+H in Chrome), and Back/Forward of current tab. Findings on Chrome: - New entries are added when...

According to Travis, this broke Safari on macOS. https://saucelabs.com/jobs/75971e1a7d5848d3b686b34a33f0b773

Let's see the stack trace on the later error: firepad.js:1673 Uncaught Error: sendOperation() called with invalid operation. firepad.js:1673 assert firepad.js:1430 firepad.FirebaseAdapter.FirebaseAdapter.sendOperation firepad.js:2383 firepad.EditorClient.EditorClient.sendOperation firepad.js:2087 firepad.Client.Synchronized.applyClient firepad.js:2052 firepad.Client.Client.applyClient firepad.js:2352 firepad.EditorClient.EditorClient.onChange firepad.js:2275...

This is horrific. Opening a page from 2 tabs reliably breaks sync for me. **It's likely that silent edit loss has been going on for users for don't know how...

pushing prominent warning on top linking to this bug...

progress: `Cannot read property 'line' of undefined` is coming from my render-math.js and is probably the root cause. (being my fault is much more comforting than being Firepad's fault :-))...

# OK, conclusions: ## This has been broken for half a year caused https://github.com/cben/CodeMirror-MathJax/commit/475901c0b7892a779138c5ddab7f04c3d3c945c8 where I made 2 drunk-idiot-level bugs - Editing first line of the document would AFAICT immediately...

I've pushed a fix but I'm leaving this bug open (and the warning on top leading here) until I implement #56 to reliably warn any user whose specific saving doesn't...

Good news: reproducing the problem (for #56) proved quite hard. Firepad is much more stubborn than I expected in sending and receiving changes even when there are exceptions :-) This...