Template 'StudiegidsV2_AlgemeenOpleidingLocatiegidsen' is incorrect, please contact the administrator

The following has evaluated to null or missing: ==> Studiegidsloc_AOLgidsen[0] [in template "freemarker-template" at line 1, column 19] ---- Tip: It's the final [] step that caused this error, not those before it. ---- 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</#if>. (These only cover the last step of the expression; to cover the whole expression, use parenthesis: (myOptionalVar.foo)!myDefault, (myOptionalVar.foo)?? ---- ---- FTL stack trace ("~" means nesting-related): - Failed at: #assign school = Studiegidsloc_AOLgid... [in template "freemarker-template" at line 1, column 1] ----