Added error message in print_result

UD_any/print_results.py

@@ -58,6 +58,11 @@ if __name__ == "__main__" :
         output.append(outputByModelScore[corpus][model][metric][0])
         output[-1][2] = score
 
+  if len(output) == 0 :
+    print("ERROR : Output length is 0", file=sys.stderr)
+    print("  did you run evaluate.sh ?", file=sys.stderr)
+    exit(1)
+
   maxColLens = [0 for _ in range(len(output[0]))]
 
   output = [["Corpus","Metric","F1.score","Model"]] + output