\declaremodule: Make this more robust. Only attempt to add an index

\declaremodule:  Make this more robust.  Only attempt to add an index
		 entry based on the module type if the type is known.
		 Otherwise, spit out a warning the the module type
		 parameter was bad and generate a "plain" index entry.

		 Without this, the bad module type was emitted as
		 text.

Problem noticed by processing Michael Hudson's docs for
bytecodehacks.