ircd:🆑 Check and throw for unavailability in work item ctor.

include/ircd/cl.h

@@ -23,6 +23,7 @@ namespace ircd::cl
 
 	IRCD_EXCEPTION(ircd::error, error)
 	IRCD_EXCEPTION(error, opencl_error)
+	IRCD_EXCEPTION(error, unavailable)
 
 	using read_closure = std::function<void (const_buffer)>;
 	using write_closure = std::function<void (mutable_buffer)>;
@@ -67,7 +68,7 @@ struct ircd::cl::work
 	void wait(const uint = 0);
 
 	explicit work(void *const &handle); // note: RetainEvent()
-	work() noexcept;
+	work();
 	work(work &&) noexcept;
 	work(const work &) = delete;
 	work &operator=(work &&) noexcept;

ircd/cl.cc

@@ -1938,8 +1938,14 @@ noexcept
 //
 
 ircd::cl::work::work()
-noexcept
 {
+	if(unlikely(!cl::linkage || run::level != run::level::RUN))
+		throw unavailable
+		{
+			"Unable to submit work items at this time."
+		};
+
+	assert(cl::linkage);
 	assert(ircd::run::level == run::level::RUN);
 }