chore: add support for error parser in the pretty printer

src/Lean/PrettyPrinter/Formatter.lean

@@ -191,6 +191,10 @@ st ← get;
 let stx := st.stxTrav.parents.back.getArg (st.stxTrav.idxs.back - offset);
 categoryParser.formatter stx.getId
 
+@[combinatorFormatter Lean.Parser.error]
+def error.formatter (msg : String) : Formatter :=
+pure ()
+
 @[combinatorFormatter Lean.Parser.try]
 def try.formatter (p : Formatter) : Formatter :=
 p

src/Lean/PrettyPrinter/Parenthesizer.lean

@@ -320,6 +320,10 @@ def level.parenthesizer : CategoryParenthesizer | prec => do
 maybeParenthesize `level (fun stx => Unhygienic.run `(level|($stx))) prec $
   parenthesizeCategoryCore `level prec
 
+@[combinatorParenthesizer Lean.Parser.error]
+def error.parenthesizer (msg : String) : Parenthesizer :=
+pure ()
+
 @[combinatorParenthesizer Lean.Parser.try]
 def try.parenthesizer (p : Parenthesizer) : Parenthesizer :=
 p