Catch exception when document has been removed from Knowledge Center

@ajayp, just want to add some info here. Generally, before the form is submitted using SAIL document upload field, the document is saved on the server (and not tearget KC) with an inactive temporary Id and we cannot perform any operations with that Id. Once the form is submitted using SAIL document upload field, the document is saved with a new version. This might be the possible reason for the missing document. An alternative is to have a "Upload" button which helps the document getting upload into the targeted KC directly. You will now have the actual document id, with which you can convert it into a document and perform a variety of validations.

@ajayp, just want to add some info here. Generally, before the form is submitted using SAIL document upload field, the document is saved on the server (and not tearget KC) with an inactive temporary Id and we cannot perform any operations with that Id. Once the form is submitted using SAIL document upload field, the document is saved with a new version. This might be the possible reason for the missing document. An alternative is to have a "Upload" button which helps the document getting upload into the targeted KC directly. You will now have the actual document id, with which you can convert it into a document and perform a variety of validations.