ffplay hangs if audio_thread() fails early

[Cigaes]

With the following change to simulate an early failure:

--- a/fftools/ffplay.c
+++ b/fftools/ffplay.c
@@ -2048,7 +2048,7 @@ static int audio_thread(void *arg)
     AVRational tb;
     int ret = 0;
 
-    if (!frame)
+    //if (!frame)
         return AVERROR(ENOMEM);
 
     do {

ffplay hangs when playing any audio-only file without any diagnostic.

(A similar failure can happen in real conditions, especially if the audio filter can be configured alone but not for the audio hardware parameters.)