daily scheduling bug

Original info from Maura:

The participant ND3167 who was scheduled today at 13.00 with Dorothea (for AN visit), has been postponed to the 19.04.2018 at 13.00 still with Dorothea. I changed the record in the scheduling system, but I could not make the change in the daily planning, as I cannot access it further than the 11.04.2018.

Error from JS console:

Uncaught TypeError: Cannot read property 'format' of null
    at Object.eventRender (daily_planning.827b9a7a6fdc.js:354)
    at constructor.publiclyTrigger (fullcalendar.min.bc315925a4d1.js:9)
    at t.publiclyTrigger (fullcalendar.min.bc315925a4d1.js:8)
    at t.resolveEventEl (fullcalendar.min.bc315925a4d1.js:9)
    at HTMLAnchorElement.<anonymous> (fullcalendar.min.bc315925a4d1.js:7)
    at Function.each (jquery-2.2.3.min.33cabfa15c10.js:2)
    at n.fn.init.each (jquery-2.2.3.min.33cabfa15c10.js:2)
    at Et.function.e.constructor.renderFgSegEls (fullcalendar.min.bc315925a4d1.js:7)
    at Et.function.e.constructor.renderFgSegsIntoContainers (fullcalendar.min.bc315925a4d1.js:8)
    at Et.function.e.constructor.renderFgSegs (fullcalendar.min.bc315925a4d1.js:8)