Make a coro.resume() wrapper and use in coro.launch(), coro.yield().

coro.resume() checks the ok boolean returned by coroutine.resume() and, if not
ok, propagates the error. This avoids coroutine errors getting swallowed.

1 files changed, 17 insertions, 7 deletions

diff --git a/indra/newview/scripts/lua/coro.lua b/indra/newview/scripts/lua/coro.lua
index 8f868f5a48..616a797e95 100644
--- a/indra/newview/scripts/lua/coro.lua
+++ b/indra/newview/scripts/lua/coro.lua
@@ -5,15 +5,25 @@ local coro = {}
 coro._coros = {}
 
 -- Launch a Lua coroutine: create and resume.
--- Returns:
--- new coroutine
--- bool ok
--- if not ok: error message
--- if ok:     values yielded or returned
+-- Returns: new coroutine, values yielded or returned from initial resume()
+-- If initial resume() encountered an error, propagates the error.
 function coro.launch(func, ...)
     local co = coroutine.create(func)
     table.insert(coro._coros, co)
-    return co, coroutine.resume(co, ...)
+    return co, coro.resume(co, ...)
+end
+
+-- resume() wrapper to propagate errors
+function coro.resume(co, ...)
+    -- if there's an idiom other than table.pack() to assign an arbitrary
+    -- number of return values, I don't yet know it
+    local ok_result = table.pack(coroutine.resume(co, ...))
+    if not ok_result[1] then
+        -- if [1] is false, then [2] is the error message
+        error(ok_result[2])
+    end
+    -- ok is true, whew, just return the rest of the values
+    return table.unpack(ok_result, 2)
 end
 
 -- yield to other coroutines even if you don't know whether you're in a
@@ -28,7 +38,7 @@ function coro.yield(...)
         -- Walk a copy of coro._coros in case any of these coroutines launches
         -- another: next() forbids creating new entries during traversal.
         for co in coro._live_coros_iter, table.clone(coro._coros) do
-            co.resume()
+            coro.resume(co)
         end
     end
 end