Improve test parsing error reporting.

diff --git a/src/ircplom/testing.py b/src/ircplom/testing.py
index b03b12feb131838786c137f72fa39fb6f5fb067c..3c3e1794ab02e582e30e5bada08af8f66ad832c8 100644 (file)
--- a/src/ircplom/testing.py
+++ b/src/ircplom/testing.py
@@ -209,8 +209,11 @@ class _Playbook:
                    ) -> list[tuple[str, str]]:
 
             def crop_to_range(range_str: str) -> None:
-                idx_in, idx_out = ((int(val) if val else None)
-                                   for val in range_str.split(_SEP_2))
+                try:
+                    idx_in, idx_out = ((int(val) if val else None)
+                                       for val in range_str.split(_SEP_2))
+                except ValueError as e:
+                    assert False, (e, idx_str, insert_args)
                 candidates[:] = candidates[idx_in:idx_out]
 
             def replace_pattern(to_replace: str, replacement: str) -> None: