To reproduce, load the attached APL file that provides a definition for the function io∆readfile. Then try to read the attached file called "services":
==============================================================================
Assertion failed: 0
in Function: init
in file: Cell.cc:48
Call stack:
----------------------------------------
-- Stack trace at Cell.cc:48
----------------------------------------
0x7f29383b1b05 __libc_start_main
0x434ef5 main
0x5266bd Workspace::immediate_execution(bool)
0x46235d Command::process_line()
0x46126e Command::process_line(UCS_string&)
0x46a215 Executable::execute_body() const
0x4e02d0 StateIndicator::run()
0x48a83a Prefix::reduce_statements()
0x486a24 Prefix::reduce_MISC_F_B_()
0x4e0f49 StateIndicator::eval_B(Token&, Token&)
0x48f358 Bif_F12_PARTITION::eval_B(Value_P)
0x52295b Value::clone(char const*) const
0x459b21 Cell::init(Cell const&)
0x443231 do_Assert(char const*, char const*, char const*, int)
========================================
SI stack:
Depth: 1
Exec: 0x19fafd8
Pmode: ∇ io∆readfile[25]
PC: 104 ]
Stat: result[⎕IO+row] ← ⊂⎕UCS buf
err_code: 0x0
thrown: at StateIndicator.cc:40
e_msg_1: 'No Error'
e_msg_2: ''
e_msg_3: ''
Depth: 0
Exec: 0x19fc4b0
Pmode: ◊ foo ← io∆readfile '/etc/services'
PC: 3 'foo←
Stat: foo ← io∆readfile '/etc/services'
err_code: 0x0
thrown: at StateIndicator.cc:40
e_msg_1: 'No Error'
e_msg_2: ''
e_msg_3: ''
==============================================================================
====================================================
SEGMENTATION FAULT
----------------------------------------
-- Stack trace at main.cc:122
----------------------------------------
0x7f29383b1b05 __libc_start_main
0x434ef5 main
0x5266bd Workspace::immediate_execution(bool)
0x46235d Command::process_line()
0x46126e Command::process_line(UCS_string&)
0x46a215 Executable::execute_body() const
0x4e02d0 StateIndicator::run()
0x48a83a Prefix::reduce_statements()
0x486a24 Prefix::reduce_MISC_F_B_()
0x4e0f49 StateIndicator::eval_B(Token&, Token&)
0x48f358 Bif_F12_PARTITION::eval_B(Value_P)
0x52295b Value::clone(char const*) const
0x459b21 Cell::init(Cell const&)
0x4431d9 do_Assert(char const*, char const*, char const*, int)
0x4fe15e TestFiles::assert_error()
0x7f293a409880
0x478d6a
========================================
====================================================
Process apl segmentation fault (core dumped)
io.apl