protected static VarnodeSymbol addNilSymbol(PcodeParser parser) {
		SleighSymbol exists = parser.findSymbol(NIL_SYMBOL_NAME);
		if (exists != null) {
			// A ClassCastException here indicates a name collision
			return (VarnodeSymbol) exists;
		}
		long offset = parser.allocateTemp();
		VarnodeSymbol nil = new VarnodeSymbol(new Location("<util>", 0), NIL_SYMBOL_NAME,
			parser.getUniqueSpace(), offset, 1);
		parser.addSymbol(nil);
		return nil;
	}
Add a symbol for unwanted result

<p>
This is basically a hack to avoid NPEs when no output varnode is given.

@param parser the parser to add the symbol to
@return the nil symbol
Ghidra/Framework/Emulation/src/main/java/ghidra/pcode/exec/SleighProgramCompiler.java