This is a clone of issue OCPBUGS-55076. The following is the description of the original issue:
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During the tar ball generation at the end of the m2d, if errors happens when adding a release signatures to the tar ball, it should stop the flow as it happens during the copy phase (release images will always have a signature).

For operators, additional images and helm images, if there was a signature copied during the copy phase but because of some reason it was not possible to retrieve it from the cache to add to the tar ball, it should log the error to a file (for troubleshooting) but it should not stop the flow. [Alex] Removing this requirement since there is no way currently to identify if one signature was copied for the image types operators, additional and helm images.

For signature errors during the tar ball generation, a non zero exit code should be returned.