- fixed missing checks for function calls from DECORATE

State functions could call ZScript code with incompatible self pointer, e.g. weapon's function could be called with self pointed to player pawn
DECORATE scripts that contain such errors are no longer accepted

https://forum.zdoom.org/viewtopic.php?t=66429

src/scripting/decorate/thingdef_exp.cpp

@@ -517,7 +517,8 @@ static FxExpression *ParseExpression0 (FScanner &sc, PClassActor *cls)
 						sc.UnGet();
 						ParseFunctionParameters(sc, cls, args, func, "", nullptr);
 					}
-					return new FxVMFunctionCall(new FxSelf(sc), func, args, sc, false);
+					// FxVMFunctionCall cannot be used here as it lacks some important checks
+					return new FxFunctionCall(identifier, NAME_None, args, sc);
 				}
 			}