extract_metadata: Improve error reporting

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>

scripts/extract_metadata.py

@@ -10,6 +10,7 @@ import re
 import os
 import sys
 import time
+import traceback
 
 # regex helpers
 def _regex_find_floats(pattern, data, strict=False):
@@ -113,13 +114,13 @@ class PrusaSlicer(BaseSlicer):
             data = "".join(lines[1:-1])
             if len(info) != 3:
                 self.log.append(
-                    {'MetadataError': "Error parsing thumbnail header: %s"
-                     % (lines[0])})
+                    f"MetadataError: Error parsing thumbnail"
+                    f" header: {lines[0]}")
                 continue
             if len(data) != info[2]:
                 self.log.append(
-                    {'MetadataError': "Thumbnail Size Mismatch: detected %d, "
-                     "actual %d" % (info[2], len(data))})
+                    f"MetadataError: Thumbnail Size Mismatch: "
+                    f"detected {info[2]}, actual {len(data)}")
                 continue
             parsed_matches.append({
                 'width': info[0], 'height': info[1],
@@ -291,15 +292,9 @@ SUPPORTED_DATA = [
     'first_layer_height', 'layer_height', 'object_height',
     'filament_total', 'estimated_time', 'thumbnails']
 
-
-def main(path, filename):
-    file_path = os.path.join(path, filename)
-    slicers = [s() for s in SUPPORTED_SLICERS]
-    log = []
+def extract_metadata(file_path, log):
     metadata = {}
-    if not os.path.isfile(file_path):
-        log.append("File Not Found: %s" % (file_path))
-    else:
+    slicers = [s() for s in SUPPORTED_SLICERS]
     header_data = footer_data = slicer = None
     size = os.path.getsize(file_path)
     metadata['size'] = size
@@ -328,6 +323,19 @@ def main(path, filename):
                 result = func()
                 if result is not None:
                     metadata[key] = result
+    return metadata
+
+def main(path, filename):
+    file_path = os.path.join(path, filename)
+    log = []
+    metadata = {}
+    if not os.path.isfile(file_path):
+        log.append(f"File Not Found: {file_path}")
+    else:
+        try:
+            metadata = extract_metadata(file_path, log)
+        except Exception:
+            log.append(traceback.format_exc())
     fd = sys.stdout.fileno()
     data = json.dumps(
         {'file': filename, 'log': log, 'metadata': metadata}).encode()