Race condition in page grade blocking tests

NOTE: This may be a duplicate / the same root cause as SJRK-234

A race condition present in sjrk.storyTelling.base.page is blocking properly-functioning tests for both sjrk.storyTelling.loadStoryFromParameter and sjrk.storyTelling.loadBrowse (both in storyTellingServerUI.js).

These tests were meant to be added alongside the changes described in SJRK-237, but the work required to remediate them would be substantial, hence this Jira.

To reproduce:

1. check out this branch: https://github.com/BlueSlug/sjrk-story-telling/tree/SJRK-255 (at commit cf3c37c, ideally)
2. run the database server (instructions in README)
3. run the webserver
4. navigate to http://localhost:8081/tests/html/storyTellingServerUI-Tests.html

Expected: all tests passing, no errors

Actual: sometimes tests pass, sometimes they fail with error

On Windows 10 Pro v.1903:

• running Chrome 75, the error was not reported after 100 loads
• Firefox 68 failed 92% of the time with this message:

  TypeError: text is undefinedfluidParser.js:420:8
  XMLEncode fluidParser.js:420
      renderComponent fluidRenderer.js:980
      renderComponentSystem fluidRenderer.js:1139
      renderRecurse fluidRenderer.js:1327
      renderTemplates fluidRenderer.js:1405
      reRender fluidRenderer.js:1488
      render fluidRenderer.js:1555
      render RendererUtilities.js:104
      refreshView RendererUtilities.js:178
      invokeInvoker FluidIoC.js:1749
      togo FluidIoC.js:1813
      fire Fluid.js:1596
      finishInit PrefsEditor.js:469
      then FluidPromises.js:33
      finishInit PrefsEditor.js:467
      init PrefsEditor.js:488
  

• Edge 44 failed 59% of the time with this error message

  0: Unable to get property 'replace' of undefined or null reference