How to avoid `Pattern not found` message and screen redraw in `less` (as Git pager)

I just hacked my core.pager to show me more usefull log and diff:

[core]
; diff-so-fancy:
;   Seperate files in diff view
; LESS_TERMCAP ... +0 -p ...:
;   Highlight merge commits and file beginnings in diff view (but do not
;   jump because of `+0`), press `n` to jump to the next occurence
; -S:
;   Do not break long lines (useful for log --graph with branches)
pager = "diff-so-fancy | LESS_TERMCAP_so=$'\\E[1;37m' less --tabs=4 -RFX +0 -p 'Merge (branch|pull request) .*|^(added|deleted|modified): '"

It's quite cool, but I don't like some behaviour of less. How can I prevent

• Pattern not found message (for example when running git diff on a clean repo)?
• redraw of the full screen (git log --oneline -5)?
• the need of pressing q even on half screen messages (because of -S)?

Note that if you want to use it without diff-so-fancy, then change ^(added|deleted|modified) to ^diff --git.

A SIMPLIFIED SOLUTION

pager = "diff-so-fancy | GREP_COLOR='1;37' grep --color=always -E 'Merge (branch|pull request).*|$' | less --tabs=4 -RFX"

It will only highlight merge commits, does nothing more.