only use shape.radius if availible; fixes #1625 (#2005)

lib/network/modules/components/physics/BarnesHutSolver.js

@@ -115,7 +115,7 @@ class BarnesHutSolver {
       dx = distance;
     }
 
-    if (this.overlapAvoidanceFactor < 1) {
+    if (this.overlapAvoidanceFactor < 1 && node.shape.radius) {
       distance = Math.max(0.1 + (this.overlapAvoidanceFactor * node.shape.radius), distance - node.shape.radius);
     }
 
@@ -462,4 +462,4 @@ class BarnesHutSolver {
 }
 
 
-export default BarnesHutSolver;
+export default BarnesHutSolver;

lib/network/modules/components/physics/FA2BasedRepulsionSolver.js

@@ -21,7 +21,7 @@ class ForceAtlas2BasedRepulsionSolver extends BarnesHutSolver {
       dx = distance;
     }
 
-    if (this.overlapAvoidanceFactor < 1) {
+    if (this.overlapAvoidanceFactor < 1 && node.shape.radius) {
       distance = Math.max(0.1 + (this.overlapAvoidanceFactor * node.shape.radius), distance - node.shape.radius);
     }
 
@@ -37,4 +37,4 @@ class ForceAtlas2BasedRepulsionSolver extends BarnesHutSolver {
   }
 }
 
-export default ForceAtlas2BasedRepulsionSolver;
+export default ForceAtlas2BasedRepulsionSolver;