install: don't search when formula is unreadable.

These formulae are detected as missing but exist in an unreadable form.

Fixes #2485

1 files changed, 4 insertions, 0 deletions

diff --git a/Library/Homebrew/formulary.rb b/Library/Homebrew/formulary.rb
index 9401f57cb..f5e6a2eb9 100644
--- a/Library/Homebrew/formulary.rb
+++ b/Library/Homebrew/formulary.rb
@@ -210,6 +210,10 @@ module Formulary
 
     def get_formula(spec, alias_path: nil)
       super
+    rescue FormulaUnreadableError => e
+      raise TapFormulaUnreadableError.new(tap, name, e.formula_error), "", e.backtrace
+    rescue FormulaClassUnavailableError => e
+      raise TapFormulaClassUnavailableError.new(tap, name, e.path, e.class_name, e.class_list), "", e.backtrace
     rescue FormulaUnavailableError => e
       raise TapFormulaUnavailableError.new(tap, name), "", e.backtrace
     end