Add test for missing private key

release.sh

@@ -13,6 +13,7 @@ function die {
 # Usage: SparkleSign testing.xml template.xml
 function SparkleSign {
     LENGTH=$(ls -l iTerm2-${NAME}.zip | awk '{print $5}')
+    test -f $PRIVKEY || die "Set PRIVKEY environment variable to point at a valid private key (not set or nonexistent)"
     ruby "../../SparkleSigningTools/sign_update.rb" iTerm2-${NAME}.zip $PRIVKEY > /tmp/sig.txt
     SIG=$(cat /tmp/sig.txt)
     DATE=$(date +"%a, %d %b %Y %H:%M:%S %z")