partial variable names are not handled correctly

[pentium10]

the ConcatExpressionCompiler works with this syntax:

• "Hello " ~ name ~ "!"
• myVar ~ "abc"

but doesn't support syntax where you have a variable that's has the same name but with some other suffix:

• myVar ~ myVar2
• myVar ~ "" ~ myVar2

//concat
echo $e = 'myVar ~ myVar2';
echo "<br/>\r\n";
$evaluator = eval($compiler->compileExpression(new Expression($e)));
$context = array(
    'myVar' => 'abc',
    'myVar2' => '123'
);

When we change myVar2 to something else it starts working.
Further on our investigation, it might the number that causes the problem. In this case a special exception should be thrown to notify the developer that the variable names are not language standards.

@Kitano @adrienbrault How this should work?