sanitycheck: Add named exceptions

Add named exceptions instead of a generic one. Should help point to the
right issue when something goes wrong.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

scripts/sanitycheck

@@ -2665,8 +2665,12 @@ class TestSuite:
             tests_to_run = len(self.instances)
             logger.info("%d tests passed already, retrying %d tests" % (total_tests - tests_to_run, tests_to_run))
 
-        except Exception:
-            logger.error("Couldn't find input file with list of tests.")
+        except KeyError as e:
+            logger.error("Key error while parsing tests file.({})".format(str(e)))
+            sys.exit(2)
+
+        except FileNotFoundError as e:
+            logger.error("Couldn't find input file with list of tests. ({})".format(e))
             sys.exit(2)
 
     def apply_filters(self, **kwargs):