fix: Attempt to provide some information for <unlabeled event> (#1397)

Author: kamilogorek

packages/raven-js/src/raven.js

@@ -616,7 +616,9 @@ Raven.prototype = {
       return;
     }
 
-    if (this._globalOptions.stacktrace || (options && options.stacktrace)) {
+    // Always attempt to get stacktrace if message is empty.
+    // It's the only way to provide any helpful information to the user.
+    if (this._globalOptions.stacktrace || options.stacktrace || data.message === '') {
       // fingerprint on msg, not stack trace (legacy behavior, could be revisited)
       data.fingerprint = data.fingerprint == null ? msg : data.fingerprint;
 
@@ -1773,6 +1775,11 @@ Raven.prototype = {
       options
     );
 
+    var ex = data.exception.values[0];
+    if (ex.type == null && ex.value === '') {
+      ex.value = 'Unrecoverable error caught';
+    }
+
     // Move mechanism from options to exception interface
     // We do this, as requiring user to pass `{exception:{mechanism:{ ... }}}` would be
     // too much

packages/raven-js/test/raven.test.js

@@ -807,6 +807,20 @@ describe('globals', function() {
       Raven._processException('TypeError', undefined, 'http://example.com', []);
       assert.isTrue(Raven._send.called);
     });
+
+    // `throw ''` scenario. TraceKit always defaults to '' for message and 'null' for name if not parseable
+    // It's required to preserve minimal (1 frame only) stack on the server and let user to see
+    // at least something, otherwise whole exception interface will be dropped
+    // and nothing will allow user to determine where this error came from
+    it('should override message if neither type or message are present', function() {
+      this.sinon.stub(Raven, '_send');
+
+      Raven._processException(null, '', 'http://example.com', []);
+      assert.equal(
+        Raven._send.lastCall.args[0].exception.values[0].value,
+        'Unrecoverable error caught'
+      );
+    });
   });
 
   if (supportsPromiseRejectionEvent()) {
@@ -3122,6 +3136,19 @@ describe('Raven (public API)', function() {
         // but wrapped in an array
         assert.deepEqual(fingerprint, ['foo']);
       });
+
+      it('should get collected if captureMessage was called with an empty string', function() {
+        this.sinon.stub(Raven, 'isSetup').returns(true);
+        this.sinon.stub(Raven, '_send');
+
+        function foo() {
+          Raven.captureMessage('');
+        }
+
+        foo();
+        var data = Raven._send.lastCall.args[0];
+        assertSynthetic(data.stacktrace.frames);
+      });
     });
   });