SQL syntax highlightning don't work for single backslash '\'

When I have somewhere in text value single backslash char, then everything
behind this char will not be highlighted correct.

Simple example 1:

SELECT '\';

Simple example 2:

-- Test 1

SELECT a || '\' || b

UNION ALL

-- Test 2

SELECT c || '\' || d;

Screenshots of syntax highlighting:

Single backslash:

Dual backslash:

pgAdmin 4 v1.5

Desktop Runtime

Windows 10 x64 1511