avfilter/avfilter: Actually error out on init error

Currently an error from init could be overwritten by successfully
setting the enable expression.

Reviewed-by: Nicolas George <george@nsup.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavfilter/avfilter.c

@@ -924,6 +924,8 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
         ret = ctx->filter->init(ctx);
     else if (ctx->filter->init_dict)
         ret = ctx->filter->init_dict(ctx, options);
+    if (ret < 0)
+        return ret;
 
     if (ctx->enable_str) {
         ret = set_enable_expr(ctx, ctx->enable_str);
@@ -931,7 +933,7 @@ int avfilter_init_dict(AVFilterContext *ctx, AVDictionary **options)
             return ret;
     }
 
-    return ret;
+    return 0;
 }
 
 int avfilter_init_str(AVFilterContext *filter, const char *args)