complex item keys break trigger expression parsing

full expression that breaks trigger parsing :

{A Test Host 2:a.last(0)}

=0&

{A Test Host 2:a[].last(0)}

=0&

{A Test Host 2:a,.last(0)}

=0&{A Test Host 2:a,`<sub>!@#$%<sup>&()=[]{}|;:'",<.>/?.last(0)}=0&{A Test Host 2:a[,`</sup></sub>!@#$%&()=[]{}|;:'",<.>/?].last(0)}=0

Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' .last(0)}=0&{A Test Host 2:a,`<sub>!@#$%<sup>&()=[]{}|;:'",<.>/?.last(0)}=0&{A Test Host 2:a[,`</sup></sub>!@#$%&()=[]{}|;:'",<.>/?].last(0)}=0 '
Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' >/?.last(0)}=0&{A Test Host 2:a[,`~!@#$%^&*()-_=+[]{}|;:'",<.>/?].last(0)}=0 '
Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' `<sub>!@#$%<sup>&()=[]{}|;:'",<.>/?.last(0)}=0&{A Test Host 2:a[,`</sup></sub>!@#$%&()=[]{}|;:'",<.>/?].last(0)}=0 '
Unnecessary symbols detected: Check expression part starting from ' {}|;:'",<.>/?].last(0)}=0 '
Host key does not exist. Check expression part starting from ' :a[,`~!@#$%^&*()-_=+[]{}|;:'",<.>/?].last(0)}=0 '
Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' '",<.>/?].last(0)}=0 '
Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' >/?].last(0)}=0 '
Not allowed symbols or sequence of symbols in expression element detected: Check expression part starting from ' <.>/?].last(0)}=0 '
Trigger [test-a ]: cannot create