fixes in jpeg export, reload_ext function

Author: Elias Werner

jumper_extension/adapters/visualizer/backends/plotly.py

@@ -309,8 +309,20 @@ def _render_direct_plot(
                 ".jpeg"
             ):
                 save_jpeg += ".jpg"
-            fig.write_image(save_jpeg, format="jpeg", scale=2)
-            print(f"Plot saved as JPEG: {save_jpeg}")
+            try:
+                fig.write_image(save_jpeg, format="jpeg", scale=2)
+                print(f"Plot saved as JPEG: {save_jpeg}")
+            except Exception as e:
+                logger.warning(
+                    "Failed to save JPEG to %s: %s. "
+                    "JPEG export requires a working Chrome/Chromium for kaleido. "
+                    "If you are on Linux with snap-installed Chromium, the snap "
+                    "sandbox often blocks kaleido; try running `choreo_get_chrome` "
+                    "once to install a known-working Chrome, or install a non-snap "
+                    "Chrome/Chromium build.",
+                    save_jpeg,
+                    e,
+                )
 
         if pickle_file:
             if not pickle_file.endswith(".pkl"):

jumper_extension/monitor/backends/thread/monitor.py

@@ -187,6 +187,9 @@ def start(self, interval: float = 1.0):
         )
 
     def stop(self):
+        if self.start_time is None:
+            self.running = False
+            return
         self.running = False
         if hasattr(self, "_stop_event"):
             self._stop_event.set()

jumper_extension/utilities.py

@@ -18,9 +18,13 @@ def filter_perfdata(cell_history_data, perfdata, compress_idle=True):
     if cell_history_data is None or cell_history_data.empty:
         return perfdata.iloc[0:0]
 
-    # Guard against perfdata collected before the time column was introduced
+    # Guard against perfdata collected before the time column was introduced.
+    # Stay silent when perfdata is empty — that just means no samples were
+    # collected yet (e.g. monitor not running or cells too short) and the
+    # downstream "no performance data" message already covers it.
     if "time" not in perfdata.columns:
-        logger.warning("[JUmPER]: perfdata is missing 'time' column")
+        if not perfdata.empty:
+            logger.warning("[JUmPER]: perfdata is missing 'time' column")
         return perfdata.iloc[0:0]
 
     if compress_idle: