The Error is a huge verse that is 100% Glitchonicite.
When The Error was only a small verse inside a Cosmic Complex, it was relatively stable. There was quite some life, and they had an advanced civilization. However in 8 OYC, the verse got struck by a huge chunk of Glitchonicite, presumably from a corrupted verse, and The Error got corrupted by the Glitchonicite.
The Glitchonicite soon corrupted the entire verse, killing all life in the process. The Error glitched out of its Cosmic Complex, soon corrupting the entire complex. It then proceeded to swallow the Complex System. The only reason why the Complex System was safe was due to its extremely strong barrier blocking out all of the Glitchonicite. The Error has not gotten any more stable as of today.
The Error, from the inside appears to be a swirling mess of colors, probably from small outer verses and the one Cosmic Complex it corrupted a long time ago. The reason it has never been viewed from the outside of because it constantly changes size randomly and flings huge pieces of Glitchonicite everywhere, making taking pictures of it from the outside extremely dangerous.