Update exit code check for format validation

build/main.sh

@@ -3,10 +3,11 @@
 echo "running format validation..."
 ./validate.rb ../README.md
 
-if ["$?" == 0]; then
-    echo "format validation PASSED"
+if [[ $? != 0 ]]; then
+    echo "format validation failed!"
+    exit $?
 else
-    echo "format validation FAILED"
+    echo "format validation passed!"
 fi
 
 if [ "$TRAVIS_BRANCH" == "master" ]; then