More detailed error message when the toolchain used by an experiment is invalid

beat/core/experiment.py

@@ -439,8 +439,8 @@ class Experiment(object):
 
     if self.toolchain.errors:
       if self.storage is not None:
-        self.errors.append("toolchain `%s' is not valid" % \
-                self.storage.toolchain)
+        self.errors.append("toolchain `%s' is not valid, because:\n  * %s" % \
+                (self.storage.toolchain, '\n  * '.join(self.toolchain.errors)))
       else:
         self.errors.append("toolchain data is not valid, because:\n  * %s" \
                 % '\n  * '.join(self.toolchain.errors))