From bbae41749518d7f1f7c5b5b60569ec1a7c15acb4 Mon Sep 17 00:00:00 2001
From: Cody Tapscott <84105208+topolarity@users.noreply.github.com>
Date: Mon, 13 May 2024 09:09:22 -0400
Subject: [PATCH] show: improve processed StackTrace check (#54381)

This change is necessary for widely-typed vectors of stack traces to
work correctly:
```julia
Base.show_backtrace(stdout, convert(Vector{Any}, Base.stacktrace()))
```

which currently outputs a confusing error:
```julia
Stacktrace:
ERROR: MethodError: no method matching iterate(::Base.StackTraces.StackFrame)
...
```
---
 base/errorshow.jl | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/base/errorshow.jl b/base/errorshow.jl
index b06052433ffc4..567339c668600 100644
--- a/base/errorshow.jl
+++ b/base/errorshow.jl
@@ -800,7 +800,7 @@ function show_backtrace(io::IO, t::Vector)
     end
 
     # t is a pre-processed backtrace (ref #12856)
-    if t isa Vector{Any}
+    if t isa Vector{Any} && (length(t) == 0 || t[1] isa Tuple{StackFrame,Int})
         filtered = t
     else
         filtered = process_backtrace(t)