[Offscreen] Improve solving robustness.

Author: yannchevalier

samples/offscreen-interactivity/src/main/java/com/myscript/iink/demo/inksample/ui/InkViewModel.kt

@@ -348,8 +348,14 @@ class InkViewModel(
                     recognitionRoot.elements?.forEach { element ->
                         if (element.expressions != null) {
 
+                            val isSolvable = try {
+                                offscreenEditor?.mathSolverController?.getAvailableActions(element.id)?.contains("numerical-computation") == true
+                            } catch (e: IllegalArgumentException) {
+                                false
+                            }
+
                             // If possible, get solver output and strokes.
-                            if (offscreenEditor?.mathSolverController?.getAvailableActions(element.id)?.contains("numerical-computation") == true) {
+                            if (isSolvable) {
                                 val solverJIIX = offscreenEditor?.mathSolverController?.getActionOutput(element.id, "numerical-computation", MimeType.JIIX, engine?.createParameterSet()?.apply {
                                     setBoolean("export.jiix.strokes", true);
                                 })