From 536aff61ff6996149f7c3a9163717d6b1fe05122 Mon Sep 17 00:00:00 2001
From: Herman Sletmoen <hermansletmoen@gmail.com>
Date: Thu, 18 Jul 2024 14:26:49 +0200
Subject: [PATCH] Show all unknowns missing guesses; not only the first

---
 src/systems/diffeqs/abstractodesystem.jl | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/src/systems/diffeqs/abstractodesystem.jl b/src/systems/diffeqs/abstractodesystem.jl
index 001c7b82a7..8d6817a3d4 100644
--- a/src/systems/diffeqs/abstractodesystem.jl
+++ b/src/systems/diffeqs/abstractodesystem.jl
@@ -1567,11 +1567,9 @@ function InitializationProblem{iip, specialize}(sys::AbstractODESystem,
     defs = defaults(isys)
 
     # Check that all unknowns have guesses
-    # TODO: which, if any, unknowns should be excluded from this guess?
-    for x in unknowns(isys)
-        x in keys(guesses) || x in keys(defs) ||
-            throw(ArgumentError("Missing guess for $x."))
-    end
+    unknowns_missing = setdiff(unknowns(isys), [keys(guesses), keys(defs)])
+    !isempty(unknowns_missing) &&
+        throw(ArgumentError("Missing guesses for unknowns $(join(unknowns_missing, ", "))."))
 
     u0map = merge(guesses, u0map)
     if neqs == nunknown