Android ActivityNotFoundException failing to catch on Intent in OS 4.1.2 (works on 4.0.3)?

Android ActivityNotFoundException failing to catch on Intent in OS 4.1.2
(works on 4.0.3)?

Thanks for taking a look. I am a very old programmer but absolute newbie
to Android/Java. Although I haven't found a way to make code colorful and
pretty here yet ;).
I am starting an activity to open a file with a bogus/fake extension (mime
type) so I can force this ActivityNotFoundException exception (to test).
Somehow, this exception never happens on my Samsung Galaxy S3 (OS 4.1.2).
Adobe Reader opens up and errors that the file is not a PDF (it's not).
However on an older ASUS Transformer tablet running 4.0.3 the exception is
caught properly.
The code in question is like so:
// this file exists (check omitted)..
File docFile = new File("/path/to/file.bogusextension");
// intent
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
// getting doc Uri
Uri fileUri = Uri.fromFile(docFile);
// getting doc mimeType
MimeTypeMap mime = MimeTypeMap.getSingleton();
String extension = MimeTypeMap.getFileExtensionFromUrl(fileUrl);
String mimeType = mime.getMimeTypeFromExtension(extension);
intent.setDataAndType(fileUri, mimeType);
// this is for an adobe native extension, just getting FREContext
// in the class below and mapping functions
DocLauncherExtensionContext extensionContext =
(DocLauncherExtensionContext) context;
Activity activity = extensionContext.getActivity();
try
{
activity.startActivity(intent);
returnValue = FREObject.newObject(true);
}
catch (ActivityNotFoundException e)
{
Toast.makeText(context.getActivity(), "This never happens!",
Toast.LENGTH_LONG).show();
}
Is there anything blatent wrong with this code that would allow a file
with any extension what-so-ever to be constantly thrown at Adobe Reader? I
have cleared my defaults (Settings->Application Manager->Reset).
Everything I startActivity is just hurled at Adobe Reader.
Any thoughts appreciated! Thank you!