ExceptionsManager: Handle null filenames in symbolicated stack trace gracefully

Summary: If some stack frames in a trace fail to symbolicate (or are genuinely unmapped), their `frame` field will be null, and `ExceptionsManager.js` will currently crash. This diff lets it recover gracefully and show whatever information is available.

Reviewed By: dcaspi

Differential Revision: D15296220

fbshipit-source-id: 2b1006b1354295171b25bfc6230c5b3e0c57f67f

Author: motiz88

Libraries/Core/ExceptionsManager.js

@@ -46,7 +46,9 @@ function reportException(e: ExtendedError, isFatal: boolean) {
         .then(prettyStack => {
           if (prettyStack) {
             const stackWithoutInternalCallsites = prettyStack.filter(
-              frame => frame.file.match(INTERNAL_CALLSITES_REGEX) === null,
+              frame =>
+                frame.file &&
+                frame.file.match(INTERNAL_CALLSITES_REGEX) === null,
             );
             ExceptionsManager.updateExceptionMessage(
               message,