createDefaultInitForGlobal = globalType => {
	if (globalType.valtype[0] === "i") {
		// create NumberLiteral global initializer
		return t.objectInstruction("const", globalType.valtype, [
			t.numberLiteralFromRaw(66)
		]);
	} else if (globalType.valtype[0] === "f") {
		// create FloatLiteral global initializer
		return t.objectInstruction("const", globalType.valtype, [
			t.floatLiteral(66, false, false, "66")
		]);
	}
	throw new Error(`unknown type: ${globalType.valtype}`);
}
Creates an init instruction for a global type
@param {t.GlobalType} globalType the global type
@returns {t.Instruction} init expression