Index: code/parse/lua.cpp
===================================================================
--- code/parse/lua.cpp	(revision 7267)
+++ code/parse/lua.cpp	(working copy)
@@ -12221,6 +12221,11 @@
 				pi.type = PARTICLE_SMOKE2;
 				break;
 			case LE_PARTICLE_BITMAP:
+				if (pi.optional_data < 0)
+				{
+					LuaError(L, "Invalid texture specified for createParticle()!");
+				}
+
 				pi.type = PARTICLE_BITMAP;
 				break;
 		}