avoid NULL as parameter to lua_concat in llthread_log

2 files changed, 35 insertions, 10 deletions

diff --git a/src/llthread.c b/src/llthread.c
index 57f8dc3..a3b3216 100644
--- a/src/llthread.c
+++ b/src/llthread.c
@@ -132,11 +132,12 @@ static int fail(lua_State *L, const char *msg){
 void llthread_log(lua_State *L, const char *hdr, const char *msg){
   int top = lua_gettop(L);
   lua_rawgetp(L, LUA_REGISTRYINDEX, LLTHREAD_LOGGER_HOLDER);
+  if (!msg) 
+    msg = "(no error message)";
   if(lua_isnil(L, -1)){
     lua_pop(L, 1);
     fputs(hdr,  stderr);
-    if (msg) fputs(msg,  stderr);
-    else     fputs("(no error message)",  stderr);
+    fputs(msg,  stderr);
     fputc('\n', stderr);
     fflush(stderr);
     return;
diff --git a/test/test_error.lua b/test/test_error.lua
index 1407ea8..341105e 100644
--- a/test/test_error.lua
+++ b/test/test_error.lua
@@ -5,13 +5,37 @@ local include = utils.thread_init .. [[
 local llthreads = require"llthreads"
 ]]
 
-local thread = llthreads.new(include .. [[
-  error({})
-]])
-
-thread:start()
-local ok, err = thread:join()
-print(ok, err)
-assert(not ok)
+do
+    local thread = llthreads.new(include .. [[
+      error({})
+    ]])
+    
+    thread:start()
+    local ok, err = thread:join()
+    print(ok, err)
+    assert(not ok)
+end
+do
+    local thread = llthreads.new(include .. [[
+      llthreads.set_logger(function(msg) print("XXX", msg) end)
+      error({})
+    ]])
+    
+    thread:start()
+    local ok, err = thread:join()
+    print(ok, err)
+    assert(not ok)
+end
+do
+    local thread = llthreads.new(include .. [[
+      llthreads.set_logger(function(msg) end)
+      error({})
+    ]])
+    
+    thread:start()
+    local ok, err = thread:join()
+    print(ok, err)
+    assert(not ok)
+end
 print("Done!")