Warn when element is missing in devtool

src/renderers/shared/devtools/ReactComponentTreeDevtool.js

@@ -14,6 +14,7 @@
 var ReactCurrentOwner = require('ReactCurrentOwner');
 
 var invariant = require('invariant');
+var warning = require('warning');
 
 var tree = {};
 var unmountedIDs = {};
@@ -67,7 +68,13 @@ function describeID(id) {
   if (ownerID) {
     ownerName = ReactComponentTreeDevtool.getDisplayName(ownerID);
   }
-  return describeComponentFrame(name, element._source, ownerName);
+  warning(
+    element,
+    'ReactComponentTreeDevtool: Missing React element for debugID %s when ' +
+    'building stack',
+    id
+  );
+  return describeComponentFrame(name, element && element._source, ownerName);
 }
 
 var ReactComponentTreeDevtool = {

src/renderers/shared/devtools/__tests__/ReactComponentTreeDevtool-test.js

@@ -1716,7 +1716,7 @@ describe('ReactComponentTreeDevtool', () => {
     expect(ReactComponentTreeTestUtils.getRegisteredDisplayNames()).toEqual([]);
   });
 
-  it('creates stack addenda', () => {
+  it('creates current stack addenda', () => {
     function getAddendum(element) {
       var addendum = ReactComponentTreeDevtool.getCurrentStackAddendum(element);
       return addendum.replace(/\(at .+?:\d+\)/g, '(at **)');
@@ -1789,4 +1789,30 @@ describe('ReactComponentTreeDevtool', () => {
       '\n    in R (created by Q)'
     );
   });
+
+  it('creates stack addenda by ID', () => {
+    function getAddendum(id) {
+      var addendum = ReactComponentTreeDevtool.getStackAddendumByID(id);
+      return addendum.replace(/\(at .+?:\d+\)/g, '(at **)');
+    }
+
+    class Q extends React.Component {
+      render() {
+        return null;
+      }
+    }
+
+    var q = ReactDOM.render(<Q />, document.createElement('div'));
+    expect(getAddendum(ReactInstanceMap.get(q)._debugID)).toBe(
+      '\n    in Q (at **)'
+    );
+
+    spyOn(console, 'error');
+    getAddendum(-17);
+    expect(console.error.calls.count()).toBe(1);
+    expect(console.error.calls.argsFor(0)[0]).toBe(
+      'Warning: ReactComponentTreeDevtool: Missing React element for debugID ' +
+      '-17 when building stack'
+    );
+  });
 });