Retry with failover lambda for FunctionError and status > 299

For all FunctionErrors, and for invoke errors (status > 299) we
want to retry with failover lambda.

We are doing this, because if there is a connection or other error
with one lambda, the failover lambda may still work and it's
worth trying.

With time, we will probably have more complex retry flow, depending
on the error and even maybe differing for each MNO (broadcast provider).

app/clients/cbc_proxy.py

@@ -112,12 +112,10 @@ class CBCProxyClientBase(ABC):
         payload_bytes = bytes(json.dumps(payload), encoding='utf8')
         result = self._invoke_lambda(self.lambda_name, payload_bytes)
 
-        if 'FunctionError' in result:
-            if result['Payload']['errorType'] == "CBCNewConnectionError":
-                current_app.logger.info(f"Got CBCNewConnectionError for {self.lambda_name}, calling failover lambda")
-                result = self._invoke_lambda(self.failover_lambda_name, payload_bytes)
-            else:
-                raise CBCProxyException('Function exited with unhandled exception')
+        if not result:
+            failover_result = self._invoke_lambda(self.failover_lambda_name, payload_bytes)
+            if not failover_result:
+                raise CBCProxyException(f'Lambda failed for both {self.lambda_name} and {self.failover_lambda_name}')
 
         return result
 
@@ -128,12 +126,24 @@ class CBCProxyClientBase(ABC):
             InvocationType='RequestResponse',
             Payload=payload_bytes,
         )
+        current_app.logger.info(f"Finished calling lambda {lambda_name}")
 
         if result['StatusCode'] > 299:
-            raise CBCProxyException('Could not invoke lambda')
+            current_app.logger.info(
+                f"Error calling lambda {self.lambda_name} with status code { result['StatusCode']}, {result.get('Payload')}"
+            )
+            success = False
 
-        current_app.logger.info(f"Finished calling lambda {lambda_name}")
-        return result
+        elif 'FunctionError' in result:
+            current_app.logger.info(
+                f"Error calling lambda {self.lambda_name} with function error { result['Payload'] }"
+            )
+            success = False
+
+        else:
+            success = True
+
+        return success
 
     def infer_language_from(self, content):
         if non_gsm_characters(content):