More simple way to reproduce:

#(2) select: [:i| i]

Problem somehow related to mustBeBoolean error. If you try debug

#(2) select: [:i| i / 0]

Debugger will fallback into #/ method at ZeroDivide statement. But with mustBeBoolean trick it's not work.

2017-02-07 8:03 GMT+01:00 Stephane Ducasse <stepharo.self@gmail.com>:

tx for the report hilaire.��
Indeed I can reproduce your bug
- I pasted it
- I did debug it
over over and through trhough and my system froze.��

On Mon, Feb 6, 2017 at 7:04 PM, Hilaire <hilaire@drgeo.eu> wrote:
Hello,

The faulty code bellow when debugged and 'step through' cause the
debugger to hang:

self inform: '1'.
#(2 3 4) select: [:i| i] thenDo: [:n| self inform: n printString ].
self inform: '5'.

It seems trapped in an infinite loop, you can more or less get control
back with Alt+[.]

When step in, the debugger properly report the error.

Pharo #60362.

I did not see similar bug report, shall I?

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Dr. Geo
http://drgeo.eu