JS: ATNConfig can incorrectly change "alt" of 0 to null
JS: ATNConfig can incorrectly change "alt" of 0 to null

When an ATNConfig instance is created with an alt of 0, it is
possible for it to be incorrectly changed to null due to its
"falsey" nature.

wjkohnen/antlr4,parrt/antlr4,antlr/antlr4,antlr/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,chandler14362/antlr4,chandler14362/antlr4,chandler14362/antlr4,chandler14362/antlr4,wjkohnen/antlr4,parrt/antlr4,chandler14362/antlr4,antlr/antlr4,antlr/antlr4,ericvergnaud/antlr4,parrt/antlr4,Pursuit92/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,parrt/antlr4,antlr/antlr4,parrt/antlr4,antlr/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,ericvergnaud/antlr4,Pursuit92/antlr4,wjkohnen/antlr4,parrt/antlr4,Pursuit92/antlr4,Pursuit92/antlr4,ericvergnaud/antlr4,chandler14362/antlr4,ericvergnaud/antlr4,chandler14362/antlr4,Pursuit92/antlr4,parrt/antlr4,antlr/antlr4,chandler14362/antlr4,Pursuit92/antlr4,antlr/antlr4,Pursuit92/antlr4,ericvergnaud/antlr4,parrt/antlr4,Pursuit92/antlr4,parrt/antlr4,parrt/antlr4,ericvergnaud/antlr4,ericvergnaud/antlr4,wjkohnen/antlr4,antlr/antlr4,Pursuit92/antlr4,wjkohnen/antlr4,wjkohnen/antlr4,antlr/antlr4,chandler14362/antlr4