[F] Fix multiple crash bugs in the Python fallback

termenv.py:
- unix_detect_ansi_mode: `TERM`/`COLORTERM` can be absent from the
  environment (CI, cron, some IDEs). `os.environ.get('TERM')` returns
  None in that case, so subsequent `term.startswith(...)` and
  `'256color' in term` calls raised AttributeError. Changed to
  `os.environ.get('TERM') or ''` for both variables.
- unix_read_osc: same None dereference on line 99 (`term.startswith`).
  Applied the same `or ''` guard.
- unix_read_osc: `code.lstrip(start)` was used to strip the OSC prefix,
  but `str.lstrip` strips individual *characters*, not a prefix string,
  so it could silently over-consume leading bytes of the actual payload.
  Replaced with an explicit `code[len(start):]` slice after a
  `startswith` check.
- windows_detect_ansi_mode: `map(int, platform.version().split('.'))`
  crashes with ValueError/TypeError on non-standard version strings.
  Wrapped in try/except with a safe fallback of `'rgb'`.
  `int(os.environ.get('ANSICON_VER'))` raised when the var was unset or
  non-numeric; guarded with `.isdigit()` before converting.

color_util.py:
- RGB.to_ansi: for `mode == 'ansi'` it forwarded to `to_ansi_16` which
  is an unimplemented stub (`raise NotImplementedError`). For
  `mode == 'default'` and any other unknown mode the function fell
  through and returned None, causing TypeError when callers concatenated
  the result into strings (e.g. in presets.py). Both cases now fall back
  to `to_ansi_8bit`, which is a correct and safe 256-color degradation.
  Return type annotation updated to `str`.

neofetch_util.py:
- ensure_git_bash: `git_path` returned by the `if_file(...)` chain can
  be None when no Git Bash installation is found on Windows. The
  subsequent `git_path.is_file()` then raised AttributeError instead of
  printing the friendly error message. Fixed to `if not git_path or not
  git_path.is_file():`.
- get_distro_ascii: `run_neofetch_cmd` can return None when neofetch is
  missing or exits non-zero without raising. The following `.replace()`
  call would then crash with AttributeError. Added an explicit None
  guard that prints an error and exits cleanly.
- run(): the backend dispatcher had no else/fallback branch, so an
  unknown or mistyped backend silently returned None and produced no
  output. Added `raise ValueError(f"Unknown backend: {backend!r}")`.

types.py:
- BackendLiteral was `Literal["neofetch", "fastfetch"]`, missing
  `"qwqfetch"` and `"fastfetch-old"` which are both accepted by the
  argparse parser and the run() dispatcher. Stale types caused false
  type-checker warnings for valid inputs. Updated to include all four
  supported backends.

main.py:
- select_lightness: the prompt advertises `.45` and `0.45` as valid
  decimal inputs, but the parser called `int(lightness)` first, which
  raises ValueError for any non-integer float, landing in the error
  path before the `float()` branch was ever reached. Reordered to:
  handle `%` suffix first, then `float()` for everything else, dividing
  by 100 only when the value exceeds 1.
- June/pride-month check: `os.isatty(sys.stdout.fileno())` raises
  io.UnsupportedOperation when stdout is piped or replaced (e.g. during
  testing or when output is redirected). Replaced with the pattern
  already used in termenv.py: `hasattr(sys.stdout, 'isatty') and
  sys.stdout.isatty()`.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

hyfetch/color_util.py

@@ -198,15 +198,16 @@ class RGB:
         """
         raise NotImplementedError()
 
-    def to_ansi(self, mode: AnsiMode | None = None, foreground: bool = True):
+    def to_ansi(self, mode: AnsiMode | None = None, foreground: bool = True) -> str:
         if not mode:
             mode = GLOBAL_CFG.color_mode
         if mode == 'rgb':
             return self.to_ansi_rgb(foreground)
         if mode == '8bit':
             return self.to_ansi_8bit(foreground)
-        if mode == 'ansi':
-            return self.to_ansi_16(foreground)
+        # 'ansi' (16-color) is not yet implemented; fall back to 8bit which always works.
+        # 'default' and any unknown mode also fall through here as a safe degradation.
+        return self.to_ansi_8bit(foreground)
 
     def lighten(self, multiplier: float) -> 'RGB':
         """

hyfetch/main.py

@@ -289,10 +289,12 @@ def create_config() -> Config:
                 return def_lightness
 
             try:
-                if lightness.endswith('%') or int(lightness) > 1:
-                    lightness = int(lightness[:-1]) / 100 if lightness.endswith('%') else int(lightness) / 100
+                if lightness.endswith('%'):
+                    lightness = int(lightness[:-1]) / 100
                 else:
-                    lightness = float(lightness)
+                    # Accept plain floats (.45, 0.45) and integers treated as percentages (45 → 0.45)
+                    value = float(lightness)
+                    lightness = value / 100 if value > 1 else value
                 assert 0 <= lightness <= 1
                 return lightness
 
@@ -533,7 +535,8 @@ def run():
     now = datetime.datetime.now()
     june_path = CACHE_PATH / f'animation-displayed-{now.year}'
     show_for_june = False
-    if now.month == 6 and now.year not in config.pride_month_shown and not june_path.is_file() and os.isatty(sys.stdout.fileno()):
+    stdout_is_tty = hasattr(sys.stdout, 'isatty') and sys.stdout.isatty()
+    if now.month == 6 and now.year not in config.pride_month_shown and not june_path.is_file() and stdout_is_tty:
         show_for_june = True
 
     if (args.june or show_for_june) and not config.pride_month_disable:

hyfetch/neofetch_util.py

@@ -226,7 +226,7 @@ def ensure_git_bash() -> Path:
                 or if_file("C:/Program Files/Git/bin/bash.exe")
                 or if_file("C:/Program Files (x86)/Git/bin/bash.exe"))
 
-    if not git_path.is_file():
+    if not git_path or not git_path.is_file():
         printc("&cError: Git Bash installation not found")
         sys.exit(127)
 
@@ -299,6 +299,9 @@ def get_distro_ascii(distro: str | None = None) -> str:
         cmd += f' --ascii_distro {distro}'
 
     asc = run_neofetch_cmd(cmd, True)
+    if not asc:
+        printc("&cError: Failed to get ASCII art from neofetch")
+        sys.exit(1)
 
     # Unescape backslashes here because backslashes are escaped in neofetch for printf
     asc = asc.replace('\\\\', '\\')
@@ -319,6 +322,7 @@ def run(asc: str, backend: BackendLiteral, args: str = ''):
         return run_fastfetch(asc, args, legacy=True)
     if backend == "qwqfetch":
         return run_qwqfetch(asc, args)
+    raise ValueError(f"Unknown backend: {backend!r}")
 
 
 def run_qwqfetch(asc: str, args: str = ''):

hyfetch/termenv.py

@@ -22,8 +22,8 @@ def unix_detect_ansi_mode() -> AnsiMode | None:
     if hasattr(sys.stdout, 'isatty') and not sys.stdout.isatty():
         return 'ansi'
 
-    term = os.environ.get('TERM')
-    color_term = os.environ.get('COLORTERM')
+    term = os.environ.get('TERM') or ''
+    color_term = os.environ.get('COLORTERM') or ''
 
     if color_term == 'truecolor' or color_term == '24bit':
         if term.startswith('screen') and os.environ.get('TERM_PROGRAM') != 'tmux':
@@ -61,12 +61,16 @@ def windows_detect_ansi_mode() -> AnsiMode | None:
     if os.environ.get("ConEmuANSI") == "ON":
         return 'rgb'
 
-    release, _, build = map(int, platform.version().split('.'))
+    try:
+        release, _, build = map(int, platform.version().split('.'))
+    except (ValueError, TypeError):
+        # If the version string is unparseable, assume a modern Windows with full color support.
+        return 'rgb'
     if build < 10586 or release < 10:
         # No ANSI support before Windows 10 build 10586.
         if os.environ.get('ANSICON'):
-            conv = os.environ.get('ANSICON_VER')
-            if int(conv) < 181:
+            conv = os.environ.get('ANSICON_VER') or ''
+            if conv.isdigit() and int(conv) < 181:
                 return 'ansi'
             return '8bit'
         return 'ansi'
@@ -95,7 +99,7 @@ def unix_read_osc(seq: int) -> str:
 
     # screen/tmux can't support OSC, because they can be connected to multiple
     # terminals concurrently.
-    term = os.environ.get('TERM')
+    term = os.environ.get('TERM') or ''
     if term.startswith("screen") or term.startswith("tmux"):
         raise OSCException("Screen/tmux not supported")
 
@@ -152,8 +156,12 @@ def unix_read_osc(seq: int) -> str:
     if not code.startswith(start):
         raise OSCException("Received response is not an OSC response")
 
-    # Strip starting code and termination code
-    code = code.lstrip(start).rstrip("\x1b\\").rstrip('\a')
+    # Strip starting prefix and trailing termination sequence
+    code = code[len(start):]
+    if code.endswith("\x1b\\"):
+        code = code[:-2]
+    elif code.endswith('\a'):
+        code = code[:-1]
 
     return code
 

hyfetch/types.py

@@ -5,6 +5,6 @@ except ImportError:
 
 AnsiMode = Literal['default', 'ansi', '8bit', 'rgb']
 LightDark = Literal['light', 'dark']
-BackendLiteral = Literal["neofetch", "fastfetch"]
+BackendLiteral = Literal["qwqfetch", "neofetch", "fastfetch", "fastfetch-old"]
 ColorAlignMode = Literal['horizontal', 'vertical', 'custom']
 ColorSpacing = Literal['equal', 'weighted']