global UGen inside class definition crashes

[gewang]

class Foo
{
    Gain boo => global Gain bar => dac;
}

Foo foo;

on macOS, this indeterministically crashes

ge@metroplex src % ./chuck b.ck   
(internal error) unhandled UGen add: outs: 1 ins: 0
Assertion failed: (FALSE), function add, file chuck_ugen.cpp, line 557.
zsh: abort      ./chuck b.ck
ge@metroplex src % ./chuck b.ck
Assertion failed: (inlet() != NULL), function add, file chuck_ugen.cpp, line 489.
zsh: abort      ./chuck b.ck
ge@metroplex src % ./chuck b.ck
(internal error) unhandled UGen add: outs: 1 ins: 0
Assertion failed: (FALSE), function add, file chuck_ugen.cpp, line 557.
zsh: abort      ./chuck b.ck
ge@metroplex src % ./chuck b.ck
zsh: segmentation fault  ./chuck b.ck
ge@metroplex src % ./chuck b.ck
(internal error) unhandled UGen add: outs: 1 ins: 0
Assertion failed: (FALSE), function add, file chuck_ugen.cpp, line 557.
zsh: abort      ./chuck b.ck

VM bytecode instruction dump

ge@metroplex src % ./chuck +d b.ck
[b.ck]: dumping class Foo:
[b.ck]: -------
[b.ck]: Gain boo => global Gain bar => dac;
[b.ck]: [0] Chuck_Instr_Instantiate_Object( Gain )
[b.ck]: [1] Chuck_Instr_Pre_Constructor( ctor='class Object', offset=8 )
[b.ck]: [2] Chuck_Instr_Alloc_Member_Word( 8 )
[b.ck]: [3] Chuck_Instr_Assign_Object(  )
[b.ck]: [4] Chuck_Instr_Alloc_Member_Word( 16 )
[b.ck]: [5] Chuck_Instr_UGen_Link(  )
[b.ck]: [6] Chuck_Instr_DAC(  )
[b.ck]: [7] Chuck_Instr_UGen_Link(  )
[b.ck]: [8] Chuck_Instr_Reg_Pop_Int(  )
[b.ck]: [9] Chuck_Instr_Func_Return(  )
[b.ck]: -------

[b.ck]: dumping b.ck:
[b.ck]: -------
[b.ck]: Foo foo;
[b.ck]: [0] Chuck_Instr_Instantiate_Object( Foo )
[b.ck]: [1] Chuck_Instr_Pre_Constructor( ctor='class Object', offset=0 )
[b.ck]: [2] Chuck_Instr_Pre_Constructor( ctor='class Foo', offset=0 )
[b.ck]: [3] Chuck_Instr_Alloc_Word( 0 )
[b.ck]: [4] Chuck_Instr_Assign_Object(  )
[b.ck]: [5] Chuck_Instr_Reg_Pop_WordsMulti( 2 )
[b.ck]: [6] Chuck_Instr_Release_Object2( 0 )
[b.ck]: [7] Chuck_Instr_EOC(  )
[b.ck]: -------

zsh: segmentation fault  ./chuck +d b.ck

[gewang]

FYI
this crash is circumvented if the global Gain is declared outside the class definition

global Gain bar;

class Foo
{
    Gain boo => bar => dac;
}

Foo foo;

VM instruction dump:

ge@metroplex src % ./chuck +d c.ck
[c.ck]: dumping class Foo:
[c.ck]: -------
[c.ck]: Gain boo => bar => dac;
[c.ck]: [0] Chuck_Instr_Instantiate_Object( Gain )
[c.ck]: [1] Chuck_Instr_Pre_Constructor( ctor='class Object', offset=8 )
[c.ck]: [2] Chuck_Instr_Alloc_Member_Word( 8 )
[c.ck]: [3] Chuck_Instr_Assign_Object(  )
[c.ck]: [4] Chuck_Instr_Reg_Push_Global( name='bar' )
[c.ck]: [5] Chuck_Instr_UGen_Link(  )
[c.ck]: [6] Chuck_Instr_DAC(  )
[c.ck]: [7] Chuck_Instr_UGen_Link(  )
[c.ck]: [8] Chuck_Instr_Reg_Pop_Int(  )
[c.ck]: [9] Chuck_Instr_Func_Return(  )
[c.ck]: -------

[c.ck]: dumping c.ck:
[c.ck]: -------
[c.ck]: global Gain bar;
[c.ck]: [0] Chuck_Instr_Alloc_Word_Global( name='bar' )
[c.ck]: [1] Chuck_Instr_Reg_Pop_WordsMulti( 2 )
[c.ck]: Foo foo;
[c.ck]: [2] Chuck_Instr_Instantiate_Object( Foo )
[c.ck]: [3] Chuck_Instr_Pre_Constructor( ctor='class Object', offset=8 )
[c.ck]: [4] Chuck_Instr_Pre_Constructor( ctor='class Foo', offset=8 )
[c.ck]: [5] Chuck_Instr_Alloc_Word( 8 )
[c.ck]: [6] Chuck_Instr_Assign_Object(  )
[c.ck]: [7] Chuck_Instr_Reg_Pop_WordsMulti( 2 )
[c.ck]: [8] Chuck_Instr_Release_Object2( 8 )
[c.ck]: [9] Chuck_Instr_EOC(  )
[c.ck]: -------