fix error type for var record length

ckMseed/ckMseed.py

@@ -980,7 +980,19 @@ class MainWindow(QWidget):
                             if not self.scan_type:
                                 filelist = [_file]
                             else:
-                                (startepoch, endepoch) = msfile.FirstLastTime()
+                                try:
+                                    (startepoch, endepoch) = msfile.FirstLastTime()
+                                except Exception as e:
+                                    err = ("ERROR: Cannot determine start and "
+                                           "end times.")
+                                    err1 = "\t File:" + fullname
+                                    self.write_error(err, "Read/Write", "red")
+                                    self.write_error(err1, "Read/Write")
+                                    self.add_to_dict(
+                                        self.error_dict, "Read/Write", directory, _file)
+                                    self.num_errors = self.num_errors + 1
+                                    continue
+
                                 endepoch += 1
                                 start = lstrftime('%Y:%j:%H:%M:%S',
                                                   lgmtime(startepoch))