targets: check that at least one dir to backup is given

It makes no sense to backup zero dirs and some things might break in
potentially dangerous ways if attempted.

1 files changed, 3 insertions, 0 deletions

diff --git a/lbup/targets.py b/lbup/targets.py
index ddd0257..217c253 100644
--- a/lbup/targets.py
+++ b/lbup/targets.py
@@ -44,6 +44,9 @@ class Target(ABC):
         if excludes is None:
             excludes = []
 
+        if len(dirs) < 1:
+            raise ValueError('One or more dirs to backup required')
+
         self.name     = name
         self.dirs     = dirs
         self.excludes = excludes