check existing file before appending

[leoyala]

🚀 Feature Request

If a .b2nd file already exists and new data is attempted to be written to it then a simple check on the metadata should be performed to ensure that the file is consistent before appending to it. This check should ensure that:

• All expected metadata keys are available in the file
• The length of the metadata values are the same as the number of images in the array.

If these conditions are not met, then an error message should pop-out indicating that new data cannot be written to that file and that a new name has to be indicated for the file.

🔈 Motivation

Currently, new data and metadata is appended to an existing file even if the metadata does not exist or the metadata is inconsistent, which can lead to missing metadata if the existing file is corrupted or has missing data.

🛰 Alternatives

Completely disallow appending data to an existing file.

📎 Additional context

None