From d6ba3878ab7ac801c79e447689d103745c2c6119 Mon Sep 17 00:00:00 2001
From: Mike McQuaid <mike@mikemcquaid.com>
Date: Mon, 27 Feb 2023 17:34:29 +0000
Subject: [PATCH] dev-cmd/cat: improve error message.

Fixes #14815.

Co-authored-by: Adrian Ho <the.gromgit@gmail.com>
---
 Library/Homebrew/dev-cmd/cat.rb | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/Library/Homebrew/dev-cmd/cat.rb b/Library/Homebrew/dev-cmd/cat.rb
index 6aa0c907b7..ec466c6e1a 100644
--- a/Library/Homebrew/dev-cmd/cat.rb
+++ b/Library/Homebrew/dev-cmd/cat.rb
@@ -44,6 +44,19 @@ module Homebrew
       "cat"
     end
 
+    args.named.to_paths.each do |path|
+      next path if path.exist?
+
+      path = path.basename(".rb") if args.cask?
+
+      ofail "#{path}'s source doesn't exist on disk."
+    end
+
+    if Homebrew.failed?
+      $stderr.puts "The name may be wrong, or the tap hasn't been tapped."
+      return
+    end
+
     safe_system pager, *args.named.to_paths
   end
 end