Accounted for last character being a newline when checking for EOS (we can be at the second-last character if the last one is a newline

nfa.go

@@ -90,7 +90,8 @@ func (s State) checkAssertion(str []rune, idx int) bool {
 		return idx == 0
 	}
 	if s.assert == EOS {
-		return idx == len(str)
+		// Index is at the end of the string, or it points to the last character which is a newline
+		return idx == len(str) || (idx == len(str)-1 && str[len(str)-1] == '\n')
 	}
 	if s.assert == WBOUND {
 		return isWordBoundary(str, idx)