The VM now properly aborts on critical errors

src/zscript/vm.h

@@ -156,6 +156,14 @@ enum
 	ATAG_RNG,				// pointer to FRandom
 };
 
+enum EVMAbortException
+{
+	X_READ_NIL,
+	X_WRITE_NIL,
+	X_TOO_MANY_TRIES,
+	X_ARRAY_OUT_OF_BOUNDS,
+};
+
 class VMFunction : public DObject
 {
 	DECLARE_ABSTRACT_CLASS(VMFunction, DObject);

src/zscript/vmexec.cpp

@@ -44,7 +44,7 @@
 #define ASSERTKA(x)		assert(sfunc != NULL && (unsigned)(x) < sfunc->NumKonstA)
 #define ASSERTKS(x)		assert(sfunc != NULL && (unsigned)(x) < sfunc->NumKonstS)
 
-#define THROW(x)
+#define THROW(x)		throw(EVMAbortException(x))
 
 #define CMPJMP(test) \
 	if ((test) == (a & CMP_CHECK)) { \
@@ -54,14 +54,6 @@
 		pc += 1; \
 	}
 
-enum
-{
-	X_READ_NIL,
-	X_WRITE_NIL,
-	X_TOO_MANY_TRIES,
-	X_ARRAY_OUT_OF_BOUNDS
-};
-
 #define GETADDR(a,o,x) \
 	if (a == NULL) { THROW(x); } \
 	ptr = (VM_SBYTE *)a + o

src/zscript/vmframe.cpp

@@ -407,6 +407,40 @@ int VMFrameStack::Call(VMFunction *func, VMValue *params, int numparams, VMRetur
 		}
 		throw;
 	}
+	catch (EVMAbortException exception)
+	{
+		if (allocated)
+		{
+			PopFrame();
+		}
+		if (trap != nullptr)
+		{
+			*trap = nullptr;
+		}
+
+		Printf("VM execution aborted: ");
+		switch (exception)
+		{
+		case X_READ_NIL:
+			Printf("tried to read from address zero.");
+			break;
+
+		case X_WRITE_NIL:
+			Printf("tried to write to address zero.");
+			break;
+
+		case X_TOO_MANY_TRIES:
+			Printf("too many try-catch blocks.");
+			break;
+
+		case X_ARRAY_OUT_OF_BOUNDS:
+			Printf("array access out of bounds.");
+			break;
+		}
+		Printf("\n");
+
+		return -1;
+	}
 	catch (...)
 	{
 		if (allocated)