fix: setEdgeLabelPos报错

public/static/lib/potree/potree.js

@@ -82246,7 +82246,7 @@ void main()
 	    setEdgeLabelPos(label,p1,p2){ //调整label的位置，使倾斜后看起来在线的中心，而不要挡住端点
 	        let center = new Vector3().addVectors(p1,p2).multiplyScalar(0.5);  
 	        
-	        if(this.lineDir){
+	        if(this.lineDir && this.lineDir.length() > 0){
 	            if(viewer.mainViewport.camera.type == 'OrthographicCamera'){
 	                label.setPos(center); 
 	            }else {
@@ -82272,7 +82272,7 @@ void main()
 	                    let camDirPlane = new Plane().setFromNormalAndCoplanarPoint(dir,  eyePos); 
 	                    nearPoint = ray.ray.intersectPlane(camDirPlane, new Vector3()); 
 	                    
-	                    if(!nearPoint)console.error('no?',cos, this.lineDir, p1, p2);
+	                    //if(!nearPoint)console.error('no?',cos, this.lineDir, p1, p2)
 	                }