GUI: Standalone Script Generator is stuck at reloading

[Adam-Szw]

Description

As a user of Standalone Script Generator, I don't want it to get stuck at reloading page if the Script Generator Python process crashes.

To reproduce:

• Open script generator in standalone mode,
• Delete the Python process that the Script Generator is using
• Might need playing around a little more to trigger reload
• Should be stuck at Reloading Screen now

Additionally, when running from IBEX GUI, there is no 'Reloading' page, see ticket here: #6691

Acceptance Criteria:

• After reproducing the steps, there is reloading screen and after that Script Generator comes back to normal functioning,
  with it's state intact
• Add a Squish test for this
• This behaviour is consistent when ran from IBEX GUI as well as standalone

[Adam-Szw]

This was discovered during manual tests of release 8.0.0

[LowriJenkins]

When testing another issue #5811 I have found an error that appears to causes a crash followed by being stuck at reloading, in this scenario the issue occurs on both the built in and standalone script generators. Both display the reloading screen however.

[daryakoskeroglu]

ISISComputingGroup/ibex_gui#1370

[daryakoskeroglu]

#6843

[daryakoskeroglu]

Ticket for Squish tests: #6844