Default should always be string.

Author: purple4reina

datadog_lambda/config.py

@@ -38,11 +38,7 @@ def as_bool(val):
 
 
 def as_list(val):
-    if isinstance(val, str):
-        if not val:
-            return []
-        return [val.strip() for val in val.split(",") if val.strip()]
-    return val
+    return [val.strip() for val in val.split(",") if val.strip()]
 
 
 class Config:
@@ -53,10 +49,8 @@ class Config:
     cold_start_tracing = _get_env("DD_COLD_START_TRACING", "true", as_bool)
     min_cold_start_trace_duration = _get_env("DD_MIN_COLD_START_DURATION", 3, int)
     cold_start_trace_skip_lib = _get_env(
-            "DD_COLD_START_TRACE_SKIP_LIB", [
-                "ddtrace.internal.compat",
-                "ddtrace.filters",
-            ], as_list)
+            "DD_COLD_START_TRACE_SKIP_LIB", "ddtrace.internal.compat,ddtrace.filters",
+            as_list)
 
     capture_payload_max_depth = _get_env("DD_CAPTURE_LAMBDA_PAYLOAD_MAX_DEPTH", 10, int)
     capture_payload_enabled = _get_env("DD_CAPTURE_LAMBDA_PAYLOAD", "false", as_bool)