Merge branch 'fail-fast-0-jobs' into 'master'

Clearer error when xfel-calibrate would run no jobs

See merge request !886

src/xfel_calibrate/calibrate.py

@@ -770,6 +770,9 @@ def run(argv=None):
         cvtype = get_par_attr(parms, concurrency_par, 'type', list)
         cvals = remove_duplications(cvals)
 
+        if not cvals:
+            raise ValueError("Splitting data for concurrency gave 0 jobs")
+
         for cnum, cval in enumerate(cvals):
             show_title = cnum == 0
             cval = [cval, ] if not isinstance(cval, list) and cvtype is list else cval