Reactivity minor fix, hardening

* Empty parameters array handling routine to prevent crash.

prasopes/reactivitytools.py

@@ -18,7 +18,7 @@ import logging
 matplotlib.use("Qt5Agg")
 
 
-logger = logging.getLogger('drlLogger')
+logger = logging.getLogger('reactivityLogger')
 
 def update_parselect(augCanvas, parselect):
     index = parselect.currentIndex()
@@ -53,10 +53,18 @@ def pop_dial(augCanvas, drls, graph, labels, parselect, coef1, coef2):
                 toavg.append((float(params[i][parselect.currentIndex()])
                               -coef1.value())*coef2.value())
                 lastpos = i
-            elif float(params[i][0]) > time:
+            elif float(params[i][0]) > time and i > 0:
+                # i>0 condition to handle possibility of invalid first scan.
+                # (was observed in-wild on TSQ once)
                 break
         if len(toavg) != 0:
             pressures.append([time, np.average(toavg)])
+    if len(pressures) == 0:
+        QtWidgets.QMessageBox.critical(None, "No times loaded",
+                "Did not located any valid parameters.\n"
+                "It is either start of the acquisition,\n"
+                "or the timestamps has been corrupted.")
+        return
     nptpressures = np.asarray(pressures).T[0]
     goodtimes = np.where([t in nptpressures for t in times])
     for i in range(1,len(intensities)):