[Q] Nexus 5 suddenly refuses to boot, factory reset does not help, TWRP shows error topic

Hey,

I've been running several Lollipop ROMs on my Nexus 5 in the past few months.

Today my Nova Launcher suddenly stopped working and froze instantly on restart, so I rebooted the phone.
It got stuck shortly before ending the boot, after several seconds of those colored dots whizzing around the screen they froze.
This issue was reproducible, so I first cleared the Cache and Dalvik Cache and rebooted, same problem. I then tried to Fix Permissions to no avail.

I then erased System, Data, Cache and Dalvik Cache and reflashed my current L-ROM of choice, OptiPop.
The device still doesn't boot, same problem.

Now TWRP is showing an error in red font whenever I try to wipe or flash.
The error I'm getting is:

Code:

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unable to stat '/data/data/com.google.android.feedback/cache/com.android.opengl.shaders_cache'

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Does anyone have an idea on how to fix this?