The free version allows limited "extrude along normal." It is slower for large faces but avoids cracking 90% of the time.
Before completing an operation in Joint Push Pull, check the dialog box settings: sketchup joint push pull crack
When two faces meet at an acute interior angle (like a deep V-groove), pushing them outward can cause the offset geometry to intersect itself. The tool's "crack" is actually its way of aborting a self-intersecting mess. The free version allows limited "extrude along normal
SketchUp represents curves using a series of straight line segments (facets). When a curved surface is thickened using Joint Push Pull, the plugin calculates the offset for each segment. SketchUp represents curves using a series of straight
If you need a true normal offset and see cracks:
SketchUp allows users to extend its functionality through various plugins and extensions. These can be found in the SketchUp Extension Warehouse or through third-party websites. Plugins can add new tools, improve performance, or even provide completely new functionalities to SketchUp.