ERROR: Error while invoking the "viewerUrl" JSP custom tag; see cause exception

----
FTL stack trace ("~" means nesting-related):
	- Failed at: @td.viewerUrl urlString=("harp://" + ...  [in template "harp://5bd3b6b2347bdf0001d88c18/p/pages/components/pubHeader.ftl" at line 6, column 42]
	- Reached through: #include "components/pubHeader.ftl"  [in template "harp://5bd3b6b2347bdf0001d88c18/p/pages/viewer.ftl" at line 99, column 5]
	- Reached through: @t.region.body  [in template "harp://5bd3b6b2347bdf0001d88c18/p/pages/masters/main.ftl" at line 20, column 3]
	- Reached through: @t.page master="masters/main.ftl" bod...  [in template "harp://5bd3b6b2347bdf0001d88c18/p/pages/viewer.ftl" at line 5, column 3]
----