chore: tighten error handling and dedupe a magic string from the nitpick pass

- Narrow the ProgressBar import guard to ImportError only, with a comment explaining why it stays (the module is imported standalone by the test suite outside a live ComfyUI)
- Extract the CRAFTKIT_DIALOG_ERROR: sentinel into a shared constant instead of three separate literals, use str.removeprefix
- Note that .avif/.heic can also fail on re-encode (with output_format=keep_source), not just decode

__init__.py

@@ -20,6 +20,10 @@ try:
     from server import PromptServer
 
     _dialog_lock = threading.Lock()
+    # Must match the literal 'CRAFTKIT_DIALOG_ERROR:' prefix written by the
+    # PowerShell catch block below (kept literal there to avoid brace-escaping
+    # a dense here-string).
+    _DIALOG_ERROR_PREFIX = "CRAFTKIT_DIALOG_ERROR:"
 
     async def browse_folder(request):
         import subprocess, sys
@@ -128,6 +132,7 @@ $o.Add_Shown({
         $path = [CraftKitFolderPicker]::ShowDialog($o.Handle, 'Select input folder')
         if ($path) { $script:r = $path }
     } catch {
+        # Must match _DIALOG_ERROR_PREFIX in __init__.py.
         $script:r = 'CRAFTKIT_DIALOG_ERROR:' + $_.Exception.Message
     }
     $o.Close()
@@ -153,8 +158,8 @@ $r
         finally:
             _dialog_lock.release()
 
-        if folder.startswith("CRAFTKIT_DIALOG_ERROR:"):
-            return web.json_response({"ok": False, "error": folder[len("CRAFTKIT_DIALOG_ERROR:"):]}, status=500)
+        if folder.startswith(_DIALOG_ERROR_PREFIX):
+            return web.json_response({"ok": False, "error": folder.removeprefix(_DIALOG_ERROR_PREFIX)}, status=500)
 
         if folder and os.path.isdir(folder):
             return web.json_response({"ok": True, "path": folder})

smart_batch_resize.py

@@ -6,8 +6,11 @@ import numpy as np
 import torch
 
 try:
+    # Only unavailable when this module is imported standalone outside a live
+    # ComfyUI process (e.g. the test suite); ImportError is the only expected
+    # failure here, so anything else is left to surface normally.
     from comfy.utils import ProgressBar
-except Exception:
+except ImportError:
     ProgressBar = None
 
 
@@ -18,9 +21,9 @@ INTERP_MAP = {
     "nearest":  PILImage.NEAREST,
 }
 
-# .avif/.heic decoding depends on optional Pillow plugins that may not be installed;
-# if unsupported, the per-file try/except below skips that file with a clear warning
-# instead of crashing the batch.
+# .avif/.heic decoding (and, with output_format=keep_source, re-encoding) depends on
+# optional Pillow plugins that may not be installed; if unsupported, the per-file
+# try/except below skips that file with a clear warning instead of crashing the batch.
 SUPPORTED_EXT = {".png", ".jpg", ".jpeg", ".jfif", ".webp", ".bmp", ".tiff", ".tif", ".avif", ".heic"}