Added guard to avoid writing prf intensities if they have not been ca…

…lculated.

src/dials/command_line/simple_tof_integrate.py

@@ -345,6 +345,8 @@ def valid_intensity(intensity, variance):
  )
  )
 
+ if "intensity.prf.value" not in reflections:
+ return
  with open("prf_" + filename, "w") as g:
  for i in range(len(reflections)):
  h, k, l = reflections["miller_index"][i]