Fix empty <svg /> in cleanupIDs plugin

Author: TrySound

plugins/cleanupIDs.js

@@ -65,7 +65,7 @@ exports.fn = function(data, params) {
                 }
 
                 // Don't remove IDs if the whole SVG consists only of defs.
-                if (item.isElem('svg')) {
+                if (item.isElem('svg') && item.content) {
                     var hasDefsOnly = true;
 
                     for (var j = 0; j < item.content.length; j++) {

test/svgo/_index.js

@@ -57,4 +57,8 @@ describe('svgo', () => {
     expect(result.error).to.match(/Error in parsing SVG/);
     expect(result.path).to.equal('input.svg');
   });
+  it('should handle empty svg tag', async () => {
+    const result = optimize('<svg />', { input: 'file', path: 'input.svg' });
+    expect(result.data).to.equal('<svg/>');
+  });
 });