Notice: Undefined index: title in Drupal\update\ProjectSecurityRequirement

I suddenly got this weird error after adding a new text field to a taxonomy. I thought it had something to do with cache, but clearing cache didn't help. I also deleted the field I had created, thinking that might be the cause, but the error is still there.

Something's getting mixed up with the Update module I guess. I have been working with this site for a while now and haven't seen this error before.

Tried Google but couldn't find anything helpful, so what might be the cause and the solution for this?

Here's what I got:

Notice: Undefined index: title in Drupal\update\ProjectSecurityRequirement::createFromProjectDataAndSecurityCoverageInfo() (line 103 of core/modules/update/src/ProjectSecurityRequirement.php).
Drupal\update\ProjectSecurityRequirement::createFromProjectDataAndSecurityCoverageInfo(Array, Array) (Line: 43)
update_requirements('runtime') (Line: 186)
update_page_top(Array) (Line: 336)
Drupal\Core\Render\MainContent\HtmlRenderer->buildPageTopAndBottom(Array) (Line: 135)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object) (Line: 90)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
call_user_func(Array, Object, 'kernel.view', Object) (Line: 111)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object) (Line: 156)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 68)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 106)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 85)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 52)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23)
Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 694)
Drupal\Core\DrupalKernel->handle(Object) (Line: 19)