Now more reliably throw a runtime error when indexing into a null v…

…alue.

MiniScript-cpp/src/MiniScript/MiniscriptTAC.cpp

@@ -453,6 +453,13 @@ namespace MiniScript {
 				} break;
 				case Op::NotA:
 					return Value::Truth(!opA.BoolValue());
+				case Op::ElemBofA:
+					if (opA.IsNull()) {
+						TypeException("Null Reference Exception: can't index into null").raise();
+					} else {
+						TypeException("Type Exception: can't index into this type").raise();
+					}
+
 				default:
 					break;
 			}

MiniScript-cs/MiniscriptTAC.cs

@@ -486,6 +486,12 @@ public Value Evaluate(Context context) {
 						}
 					case Op.NotA:
 						return opA != null && opA.BoolValue() ? ValNumber.zero : ValNumber.one;
+					case Op.ElemBofA:
+						if (opA is null) {
+							throw new TypeException("Null Reference Exception: can't index into null");
+						} else {
+							throw new TypeException("Type Exception: can't index into this type");
+						}
 					}
 				}
 

TestSuite.txt

@@ -993,6 +993,18 @@ a[42]
 ----------------------------------------------------------------------
 Runtime Error: __isa depth exceeded (perhaps a reference loop?) [line 3]
 ======================================================================
+==== Trap null reference lookups.
+a = null
+print a[3]
+----------------------------------------------------------------------
+Runtime Error: Null Reference Exception: can't index into null [line 2]
+======================================================================
+==== Trap null reference lookups (#2).
+a = null
+print a.foo
+----------------------------------------------------------------------
+Runtime Error: Type Error (while attempting to look up foo) [line 2]
+======================================================================
 ==== Error reporting of unexpected end-of-file.
 for i in range(0,10)
 	print i