conf: throw a specific error when PyYAML is missing

conf.py

@@ -5,7 +5,11 @@ This module is used to access the configuration of the current PyLink instance.
 It provides simple checks for validating and loading YAML-format configurations from arbitrary files.
 """
 
-import yaml
+try:
+    import yaml
+except ImportError:
+    raise ImportError("Please install PyYAML and try again.")
+
 import sys
 from collections import defaultdict
 

pylink

@@ -6,12 +6,13 @@ PyLink IRC Services launcher.
 import os
 import sys
 try:
-    from pylinkirc import world, conf, __version__
+    from pylinkirc import world
 except ImportError:
     sys.stderr.write("ERROR: Failed to import PyLink main module (pylinkirc.world).\n\nIf you are "
                      "running PyLink from source, please install PyLink first using 'python3 "
                      "setup.py install [--user]'\n")
     sys.exit(1)
+from pylinkirc import conf, __version__
 
 if __name__ == '__main__':
     import argparse