fix: resolve output from config, close #308

Author: Scrum

src/cfg-resolve.js

@@ -27,19 +27,19 @@ export default ({input, flags = {}}) => {
   }
 
   input = []
-    .concat(input || config?.input)
+    .concat(input.length > 0 ? input : config?.input)
     .filter(Boolean)
     .map(file => path.join(path.resolve(root), file));
 
   if (input.length === 0) {
     throw new TypeError('input files not found');
   }
 
-  return mergeOptions(config || {}, {
+  return mergeOptions(config ?? {}, {
     input,
-    output,
+    output: output ?? config?.output,
     options,
     root,
     allInOutput
-  }, use || {});
+  }, use ?? {});
 };