Fix incorrect error messages when certain requests fail (#1536)

- handle case where `Profile.from_id` works, but `Profile.from_username` doesn't

- Handle case where `QueryReturnedNotFoundException` lies and `similar_profiles` contains the exact username

- Still raises `ProfileNotExistsException` for compatibility.

instaloader/instaloader.py

@@ -1334,6 +1334,10 @@ class Instaloader:
                                                                                                   profile_id))
                 profile_from_id = Profile.from_id(self.context, profile_id)
                 newname = profile_from_id.username
+                if profile_name == newname:
+                    self.context.error(
+                        f"Warning: Profile {profile_name} could not be retrieved by its name, but by its ID.")
+                    return profile_from_id
                 self.context.error("Profile {0} has changed its name to {1}.".format(profile_name, newname))
                 if latest_stamps is None:
                     if ((format_string_contains_key(self.dirname_pattern, 'profile') or

instaloader/structures.py

@@ -771,6 +771,9 @@ class Profile:
             top_search_results = TopSearchResults(self._context, self.username)
             similar_profiles = [profile.username for profile in top_search_results.get_profiles()]
             if similar_profiles:
+                if self.username in similar_profiles:
+                    raise ProfileNotExistsException(
+                        f"Profile {self.username} seems to exist, but could not be loaded.") from err
                 raise ProfileNotExistsException('Profile {} does not exist.\nThe most similar profile{}: {}.'
                                                 .format(self.username,
                                                         's are' if len(similar_profiles) > 1 else ' is',