Describe the bug
I'd encountered an error upon steps following the addition of a link to text. The "To Reproduce" is one way, though it was not specifically the one I recall being the original set of steps, so there may be other potential ways for the error to be triggered.
To Reproduce
Steps to reproduce the behavior:
Pre-requisite: Copy a link to your clipboard (like the URL of this issue)
Screenshot:

Error Text:
TypeError: Cannot read property 'top' of undefined
at getCurrentCaretPositionStyle (positioned-at-selection.js:25)
at new PositionedAtSelection (positioned-at-selection.js:51)
at zf (react-dom.min.713f0afa.js:69)
at Mf (react-dom.min.713f0afa.js:87)
at ph (react-dom.min.713f0afa.js:98)
at eg (react-dom.min.713f0afa.js:125)
at fg (react-dom.min.713f0afa.js:126)
at wc (react-dom.min.713f0afa.js:138)
at fa (react-dom.min.713f0afa.js:137)
at ng (react-dom.min.713f0afa.js:149)
Pf @ react-dom.min.713f0afa.js:104
Error Location:
I tried testing this with 5.0.2 and 5.0.3 using Chrome 71.0.3578.98 and Firefox 64.0 on macOS 10.13.6 and I couldn't replicate the problem. (10s) (I must be missing something in my steps!)
@designsimply I suspect from your video the key difference being in that, at Step 6, you clicked specifically on the second block, not below it. In my testing, this seems enough to make a difference.
Aha, you are correct! Thanks for catching that and following up. 🤦♀️ I totally read step 6 as "Click below the first paragraph block" not "Click below the second paragraph block"!
Re-tested with WordPress 5.0.4-alpha-44523 and confirmed:

@aduth Is this issue still present after the removal of PositionedAtSelection? I can't reproduce any longer.
@aduth Is this issue still present after the removal of
PositionedAtSelection? I can't reproduce any longer.
It appears to be fixed! Thanks for checking.