Added more descripting message when Financialmodelingprep.com is returning empty responses

gamestonk_terminal/due_diligence/financial_modeling_prep_api.py

@@ -25,6 +25,13 @@ def rating(l_args, s_ticker):
 
         print("")
 
+    except KeyError:
+        print(
+            f"Financialmodelingprep.com is returning empty responses the ticker {s_ticker}."
+        )
+        print("")
+        return
+
     except Exception as e:
         print(e)
         print("")

tests/test_dd_financial_modeling_prep_api.py

@@ -0,0 +1,13 @@
+""" fundamental_analysis/business_insider_api.py tests """
+# noqa: F401
+import unittest
+
+# pylint: disable=unused-import
+import pytest
+
+from gamestonk_terminal.due_diligence.financial_modeling_prep_api import rating
+
+
+class TestDdFinancialModelingPrepApi(unittest.TestCase):
+    def test_rating(self):
+        rating([], "PLTR")