Don't traceback when comparing nested directories with non-directories....

Don't traceback when comparing nested directories with non-directories. (Closes: #288)

diffoscope/comparators/directory.py

@@ -253,6 +253,9 @@ class FilesystemDirectory(Directory):
     def compare(self, other, source=None):
         differences = []
 
+        if not isinstance(other, FilesystemDirectory):
+            return differences
+
         # We don't need to recurse into subdirectories; DirectoryContainer will
         # find them and do that for us.
         def list_files(path):

diffoscope/comparators/utils/compare.py

@@ -118,8 +118,10 @@ def compare_files(file1, file2, source=None, diff_content_only=False):
         file1.other_file = file2
     elif isinstance(file2, MissingFile):
         file2.other_file = file1
-    elif (file1.__class__.__name__ != file2.__class__.__name__) and (
-        file1.as_container is None or file2.as_container is None
+    elif (
+        (file1.__class__.__name__ != file2.__class__.__name__)
+        and (file1.as_container is None or file2.as_container is None)
+        and (not file1.is_directory() and not file2.is_directory())
     ):
         return file1.compare_bytes(file2, source)
     with profile("compare_files (cumulative)", file1):