Are you sure it meant phone texting and not in game chat?
I had one instance where I was playing J4 against Quinn. She used her blind on me as I E-Q combo'd her, and she dodged it really hard to the side. I was certain she must have flashed, so I called Quinn F. My jungler came to the lane to gank, and oops - she still had F. We got the kill anyways, and then pushed the wave. I stepped in to a bush to recall, then started typing in chat to apologize to my jungler and explain why I called Quinn F. Then the enemy jungler came. I thought I cancelled the text, but I died and my text had the first few characters I had typed followed by "... wwwwwwwwwwwwwweqf".
Like, oops. All because I was typing something completely reasonable to type. IDK - I feel like there needs to be a better way to react. E.g. if you start taking damage from a champion the game should automatically lock out your chat and let you use abilities again (maybe not summoners immediately so you don't accidentally flash when trying to type, but basic abilities why not).