Page Comparison

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1. Try getting all file ids from a non-existing collection
   
   1. Should fail with an appropriate error telling the existing collections.
2. Try getting the file ids from a non-existing pillar
   
   1. Should fail with an appropriate error containing the existing pillars
3. Try getting a file from a pillar in a different collection
   
   1. Should fail with an appropriate error containing the existing pillars for the collection