Improve Isearch error handling

Improve Isearch error handling

* lisp/isearch.el (isearch--momentary-message): Propertize message
suffix with minibuffer-prompt face.
(isearch--describe-regexp-mode): Do not omit description in case
of error in default non-literal search.
(isearch-message-prefix): Display “case-sensitive” in case of error.
(isearch-message-suffix): Propertize message suffix with
minibuffer-prompt face.
(isearch-search-fun-default): Remove unused error handling.

* lisp/vc/add-log.el (change-log-next-buffer): Better handle
errors during wrapping.