AP_L1_Control : Fixed potential divide by zero in Nu1 angle calculation

libraries/AP_L1_Control/AP_L1_Control.cpp

@@ -141,7 +141,7 @@ void AP_L1_Control::update_waypoint(const struct Location &prev_WP, const struct
 		
 		//Calculate Nu1 angle (Angle to L1 reference point)
 		float xtrackErr = _cross2D(A_air, AB_unit);
-		float sine_Nu1 = xtrackErr/_L1_dist;
+		float sine_Nu1 = xtrackErr/_maxf(_L1_dist , 0.1f);
 		//Limit sine of Nu1 to provide a controlled track capture angle of 45 deg
 		sine_Nu1 = constrain(sine_Nu1, -0.7854f, 0.7854f);
 		float Nu1 = asinf(sine_Nu1);