Add better error checking to misc/convert-cache.py (#14909)

Author: JukkaL

misc/convert-cache.py

@@ -8,6 +8,7 @@
 from __future__ import annotations
 
 import os
+import re
 import sys
 
 sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
@@ -36,15 +37,23 @@ def main() -> None:
 
     input_dir = args.input_dir
     output_dir = args.output_dir or input_dir
+    assert os.path.isdir(output_dir), f"{output_dir} is not a directory"
     if args.to_sqlite:
         input: MetadataStore = FilesystemMetadataStore(input_dir)
         output: MetadataStore = SqliteMetadataStore(output_dir)
     else:
+        fnam = os.path.join(input_dir, "cache.db")
+        msg = f"{fnam} does not exist"
+        if not re.match(r"[0-9]+\.[0-9]+$", os.path.basename(input_dir)):
+            msg += f" (are you missing Python version at the end, e.g. {input_dir}/3.11)"
+        assert os.path.isfile(fnam), msg
         input, output = SqliteMetadataStore(input_dir), FilesystemMetadataStore(output_dir)
 
     for s in input.list_all():
         if s.endswith(".json"):
-            assert output.write(s, input.read(s), input.getmtime(s)), "Failed to write cache file!"
+            assert output.write(
+                s, input.read(s), input.getmtime(s)
+            ), f"Failed to write cache file {s}!"
     output.commit()