use conditional imports and show help errors if modules not found

src/dailyai/transports/local_transport.py

@@ -4,17 +4,18 @@ import tkinter as tk
 
 from dailyai.transports.threaded_transport import ThreadedTransport
 
+try:
+    import pyaudio
+except ModuleNotFoundError as e:
+    print(f"Exception: {e}")
+    print(
+        "In order to use the local transport, you need to `pip install dailyai[local]`. On MacOS, you also need to `brew install portaudio`.")
+    raise Exception(f"Missing module: {e}")
+
 
 class LocalTransport(ThreadedTransport):
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
-        try:
-            global pyaudio
-            import pyaudio
-        except ModuleNotFoundError as e:
-            print(f"Exception: {e}")
-            print("In order to use the local transport, you'll need to `pip install pyaudio`. On MacOS, you'll also need to `brew install portaudio`.")
-            raise Exception(f"Missing module: {e}")
         self._sample_width = kwargs.get("sample_width") or 2
         self._n_channels = kwargs.get("n_channels") or 1
         self._tk_root = kwargs.get("tk_root") or None