Non well-founded datatype declaration randomly causes segfaults or malloc error

[tizmd]

This datatype declaration, which should be rejected because it is not well-founded, causes
a segfault at sometime, a malloc error at another execution, or silently accepted by z3.

(declare-datatypes ( (|phi[0]| 1) (|phi[1]| 1) (|phi[2]| 1) (|phi[3]| 1) (|phi[4]| 1) (|phi[5]| 1) ) (
(par (X) ( (init (value X)))) 
(par (X) ( (phi-0 (val-0 (|phi[0]| X))) ))
(par (X) ( (phi-1 (val-1 (|phi[1]| X))) (phi-5 (val-5 (|phi[5]| X)))))
(par (X) ( (phi-2 (val-2 (|phi[2]| X))) ))
(par (X) ( (phi-3-4 (val-3-4 (|phi[3]| X))) ))
(par (X) ( (phi-3-5 (val-3-5 (|phi[3]| X))) ))
))

OS: Mac OS X 10.14.6
z3 version: 4.8.5 - 64 bit

$ z3 problematic.smt2 
z3(81229,0x10dae25c0) malloc: *** error for object 0x7fd961549800: pointer being freed was not allocated
z3(81229,0x10dae25c0) malloc: *** set a breakpoint in malloc_error_break to debug
Abort trap: 6
$ z3 problematic.smt2 
$ z3 problematic.smt2 
$ z3 problematic.smt2 
Segmentation fault: 11