Remove previous button in case of single file directory

Make sure previous doesn't overlap with last item in directory

pystream/models/config.py

@@ -71,7 +71,7 @@ def parse_authorization(cls, value: Any) -> Dict[str, SecretStr]:
                 raise ValueError("input should be a valid dictionary with username as key and password as value")
         r = {}
         for k, v in val.items():
-            if len(k) < 3:
+            if len(k) < 4:
                 raise ValueError(f"[{k}: {v}] username should be at least 4 or more characters")
             if len(v) < 8:
                 raise ValueError(f"[{k}: {v}] password should be at least 8 or more characters")

pystream/models/squire.py

@@ -103,9 +103,14 @@ def get_iter(filename: pathlib.PurePath) -> Union[Tuple[str, str], Tuple[None, N
         key=lambda x: natural_sort_key(x)
     )
     idx = dir_content.index(filename.name)
-    try:
-        previous_ = dir_content[idx - 1]
-    except IndexError:
+    if idx > 0:  # 0-1 is -1, which will in turn fetch the last item from the list instead of leaving it blank
+        try:
+            previous_ = dir_content[idx - 1]
+            if previous_ == filename.name:  # This should be covered by > 0, but double check as a safety net
+                previous_ = None
+        except IndexError:
+            previous_ = None
+    else:
         previous_ = None
     try:
         next_ = dir_content[idx + 1]