PROBLEM WITH TEMPLATE, CHECK YOUR FTL (reader/pageflip/swipe.ftl):
freemarker.core.InvalidReferenceException: The following has evaluated to null or missing:
==> issue.getS3URL(issue.getName() + "-" + page, "images/pages/Page-" + page + ".jpg")  [in template "reader/pageflip/swipe.ftl" at line 42, column 45]

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Tip: If the failing expression is known to be legally refer to something that's sometimes null or missing, either specify a default value like myOptionalVar!myDefault, or use <#if myOptionalVar??>when-present<#else>when-missing. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)??
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FTL stack trace ("~" means nesting-related):
	- Failed at: #assign imageUrl = issue.getS3URL(iss...  [in template "reader/pageflip/swipe.ftl" at line 42, column 25]
	~ Reached through: #nested  [in template "templates/frontend.ftl" in macro "frontend_layout" at line 125, column 13]
	~ Reached through: @frontend_layout viewArea="vc_reader_...  [in template "reader/pageflip/swipe.ftl" at line 10, column 1]
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