diff --git a/rubin_scheduler/scheduler/schedulers/core_scheduler.py b/rubin_scheduler/scheduler/schedulers/core_scheduler.py
index c1a4783..59d0a83 100644
--- a/rubin_scheduler/scheduler/schedulers/core_scheduler.py
+++ b/rubin_scheduler/scheduler/schedulers/core_scheduler.py
@@ -97,6 +97,10 @@ def __init__(
         # Counter for observations added to the queue
         self.target_id_counter = target_id_counter
 
+        # Set to something so it doesn't fail if never set later
+        self.queue_fill_mjd_ns = -1
+        self.queue_reward_df = None
+
     def flush_queue(self):
         """Like it sounds, clear any currently queued desired observations."""
         self.queue = []
diff --git a/rubin_scheduler/scheduler/sim_runner.py b/rubin_scheduler/scheduler/sim_runner.py
index b795fce..25a4dbe 100644
--- a/rubin_scheduler/scheduler/sim_runner.py
+++ b/rubin_scheduler/scheduler/sim_runner.py
@@ -158,7 +158,11 @@ def sim_runner(
             observatory.mjd = observatory.mjd + step_none
             scheduler.update_conditions(observatory.return_conditions())
             nskip += 1
-            continue
+            # Check we didn't skip so far we should end
+            if observatory.mjd > sim_end_mjd:
+                break
+            else:
+                continue
         completed_obs, new_night = observatory.observe(desired_obs)
 
         if completed_obs is not None:
@@ -218,23 +222,26 @@ def sim_runner(
     # Only warn if it's a low-accuracy astropy conversion
     lsst = Site("LSST")
 
-    # Using pseudo_parallactic_angle, see https://smtn-019.lsst.io/v/DM-44258/index.html
-    pa, alt, az = pseudo_parallactic_angle(
-        np.degrees(observations["RA"]),
-        np.degrees(observations["dec"]),
-        observations["mjd"],
-        lon=lsst.longitude,
-        lat=lsst.latitude,
-        height=lsst.height,
-    )
-    observations["alt"] = np.radians(alt)
-    observations["az"] = np.radians(az)
-    observations["pseudo_pa"] = np.radians(pa)
-    observations["rotTelPos"] = rc._rotskypos2rottelpos(observations["rotSkyPos"], observations["pseudo_pa"])
-
-    # Also include traditional parallactic angle
-    pa = _approx_altaz2pa(observations["alt"], observations["az"], lsst.latitude_rad)
-    observations["pa"] = pa
+    if len(observations) > 0:
+        # Using pseudo_parallactic_angle, see https://smtn-019.lsst.io/v/DM-44258/index.html
+        pa, alt, az = pseudo_parallactic_angle(
+            np.degrees(observations["RA"]),
+            np.degrees(observations["dec"]),
+            observations["mjd"],
+            lon=lsst.longitude,
+            lat=lsst.latitude,
+            height=lsst.height,
+        )
+        observations["alt"] = np.radians(alt)
+        observations["az"] = np.radians(az)
+        observations["pseudo_pa"] = np.radians(pa)
+        observations["rotTelPos"] = rc._rotskypos2rottelpos(
+            observations["rotSkyPos"], observations["pseudo_pa"]
+        )
+
+        # Also include traditional parallactic angle
+        pa = _approx_altaz2pa(observations["alt"], observations["az"], lsst.latitude_rad)
+        observations["pa"] = pa
 
     runtime = time.time() - t0
     print("Skipped %i observations" % nskip)
diff --git a/tests/scheduler/test_sim_runner.py b/tests/scheduler/test_sim_runner.py
new file mode 100644
index 0000000..1bbe6e1
--- /dev/null
+++ b/tests/scheduler/test_sim_runner.py
@@ -0,0 +1,46 @@
+import logging
+import unittest
+
+import numpy as np
+
+import rubin_scheduler.utils as utils
+from rubin_scheduler.scheduler import sim_runner
+from rubin_scheduler.scheduler.model_observatory import ModelObservatory
+from rubin_scheduler.scheduler.schedulers import CoreScheduler
+from rubin_scheduler.scheduler.surveys import BaseSurvey
+
+
+class NoObsSurvey(BaseSurvey):
+    """Dummy class that always returns no valid reward"""
+
+    def calc_reward_function(self, conditions):
+        return -np.inf
+
+
+class TestSimRunner(unittest.TestCase):
+
+    def test_no_obs(self):
+        """Check that sim ends even if we stop returning observations."""
+        mjd_start = utils.SURVEY_START_MJD
+        nside = 32
+        survey_length = 1.5  # days
+
+        scheduler = CoreScheduler([NoObsSurvey([], detailers=[])])
+        observatory = ModelObservatory(nside=nside, mjd_start=mjd_start)
+        # Turn off noisy log warnings
+        logging.disable(logging.CRITICAL)
+        observatory, scheduler, observations = sim_runner(
+            observatory, scheduler, sim_duration=survey_length, filename=None
+        )
+
+        assert len(observations) == 0
+
+        observatory, scheduler, observations, reward_df, obs_rewards_series = sim_runner(
+            observatory, scheduler, sim_duration=survey_length, filename=None, record_rewards=True
+        )
+
+        assert len(observations) == 0
+
+
+if __name__ == "__main__":
+    unittest.main()