[Position Slider] Fix invalid duration setting

Fix NaN condition occurring when an invalid file is played.

Signed-off-by: Christopher Snowhill <kode54@gmail.com>

Window/PositionSlider.m

@@ -18,6 +18,8 @@
 }
 
 - (void)setMaxValue:(double)value {
+	if(isnan(value) || isinf(value)) value = 0.0; // Clip invalid values from bad file playlist entries
+
 	self.positionTextField.duration = (long)value;
 
 	[super setMaxValue:value];