Fix for issue #407: Prevent crashes due to unbounded growth.

Common/src/main/java/at/petrak/hexcasting/api/casting/eval/vm/CastingVM.kt

@@ -50,7 +50,20 @@ class CastingVM(var image: CastingImage, val env: CastingEnvironment) {
             // ...and execute it.
             // TODO there used to be error checking code here; I'm pretty sure any and all mishaps should already
             // get caught and folded into CastResult by evaluate.
-            val image2 = next.evaluate(continuation.next, world, this)
+            val image2 = next.evaluate(continuation.next, world, this).let { result ->
+                // if stack is unable to be serialized, have the result be an error
+                if (result.newData != null && IotaType.isTooLargeToSerialize(result.newData.stack)) {
+                    result.copy(
+                        newData = null,
+                        sideEffects = listOf(OperatorSideEffect.DoMishap(MishapStackSize(), Mishap.Context(null, null))),
+                        resolutionType = ResolvedPatternType.ERRORED,
+                        sound = HexEvalSounds.MISHAP,
+                    )
+                } else {
+                    result
+                }
+            }
+
             // Then write all pertinent data back to the harness for the next iteration.
             if (image2.newData != null) {
                 this.image = image2.newData

Common/src/main/java/at/petrak/hexcasting/api/casting/mishaps/MishapStackSize.kt

@@ -0,0 +1,24 @@
+package at.petrak.hexcasting.api.casting.mishaps
+
+import at.petrak.hexcasting.api.casting.eval.CastingEnvironment
+import at.petrak.hexcasting.api.casting.eval.ResolvedPatternType
+import at.petrak.hexcasting.api.casting.iota.GarbageIota
+import at.petrak.hexcasting.api.casting.iota.Iota
+import at.petrak.hexcasting.api.pigment.FrozenPigment
+import at.petrak.hexcasting.common.lib.HexDamageTypes
+import net.minecraft.world.item.DyeColor
+
+class MishapStackSize() : Mishap() {
+    override fun accentColor(ctx: CastingEnvironment, errorCtx: Context): FrozenPigment =
+        dyeColor(DyeColor.BLACK)
+
+    override fun resolutionType(ctx: CastingEnvironment) = ResolvedPatternType.ERRORED
+
+    override fun execute(env: CastingEnvironment, errorCtx: Context, stack: MutableList<Iota>) {
+        stack.clear()
+        stack.add(GarbageIota())
+    }
+
+    override fun errorMessage(ctx: CastingEnvironment, errorCtx: Context) =
+        error("stack_size")
+}

Common/src/main/resources/assets/hexcasting/lang/en_us.flatten.json5

@@ -901,6 +901,7 @@
       invalid_spell_datum_type: "Tried to use a value of invalid type as a SpellDatum: %s (class %s). This is a bug in the mod.",
       unknown: "threw an exception (%s). This is a bug in the mod.",
       shame: "Shame on you!",
+      stack_size: "Exceeded the size limit of the stack",
 
       invalid_value: {
         "": "expected %s at index %s of the stack, but got %s",