Image freeze when stepping into primitive 198

[StevenCostiou]

When using the interpreter to step code calling this primitive, the image freeze.
Stepping over the sender context of that primitive works as a workaround.

Notes:

• 198 is actually a fake primitive that always fail
• 198 is called in ensure: from blocks, but it really seems that the freezes happens within 198 when valueNoContextSwitch is called

[StevenCostiou]

It freezes here:

The workaround actually prevents Sindarin to control execution within blocks to which the ensure: message is sent.

[StevenCostiou]

So it's not the primitive itself that is the problem, but that the Semaphore keeps waiting.
It happens only when executing from the debugger and not from a test, which suggests there is some kind of interaction messing up with the Semaphore release. Or not.