From 89e6c17c13522ee3488fa4e08c8d8740458412f6 Mon Sep 17 00:00:00 2001
From: paul019 <39464035+paul019@users.noreply.github.com>
Date: Sat, 16 Mar 2024 14:28:54 +0100
Subject: [PATCH] Add error message to runtime error in rounder

---
 src/application/rounder.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/application/rounder.py b/src/application/rounder.py
index a8cc168f..d28bca77 100644
--- a/src/application/rounder.py
+++ b/src/application/rounder.py
@@ -126,7 +126,9 @@ def _round_result(cls, result: Result, config: RoundingConfig) -> None:
             value.set_min_exponent(min_exponent)
 
         else:
-            raise RuntimeError  # TODO: add message (!)
+            # This branch cannot be reached, because the config makes sure that
+            # either`sigfigs_fallback` or `decimal_places_fallback` is set.
+            raise RuntimeError("An unexpected error occurred. Please report this bug.")
 
     @classmethod
     def _uncertainties_set_min_exponents(