1238 - stop dying on run("")

This makes our scenarios more flexible; we can now accept '+' and '-'
trace lines in any order, because the tangler simply inserts a no-op
run("") between them, and since we don't '===' clear the trace in
between, later checks continue to apply to the trace from the first
call to run().

1 files changed, 1 insertions, 0 deletions

diff --git a/cpp/020run.cc b/cpp/020run.cc
index 95a8a0b1..963fcd78 100644
--- a/cpp/020run.cc
+++ b/cpp/020run.cc
@@ -137,6 +137,7 @@ load_permanently("core.mu");
 // helper for tests
 void run(string form) {
   vector<recipe_number> tmp = load(form);
+  if (tmp.empty()) return;
   transform_all();
   run(tmp.front());
 }