Do not allow parse if the <report dir> does not exist

This change prevents the CodeChecker parse command
from running if the entered report dir or filepath
parameter does not exist.
Up until now, the parse command ran with any parameters,
reporting zero findings if a wrong parameter was entered.
Fixes #4186

analyzer/codechecker_analyzer/cmd/parse.py

@@ -283,6 +283,11 @@ def main(args):
         LOG.error(fnerr)
         sys.exit(1)
 
+    for input_path in args.input:
+        if not os.path.exists(input_path):
+            LOG.error(f"Input path {input_path} does not exist!")
+            sys.exit(1)
+
     export = args.export if 'export' in args else None
     if export == 'html' and 'output_path' not in args:
         LOG.error("Argument --export not allowed without argument --output "

analyzer/tests/functional/cmdline/test_cmdline.py

@@ -250,6 +250,16 @@ def test_analyzer_config(self):
             self.assertTrue(desc)
             self.assertFalse(desc[0].islower())
 
+    def test_parse_incorrect_file_path(self):
+        """
+        This test checks whether the parse command stops running if a
+        non-existent path is specified.
+        """
+
+        parse_cmd = [env.codechecker_cmd(), 'parse', '/asd/123/qwe']
+
+        self.assertEqual(1, run_cmd(parse_cmd)[0])
+
     def test_checker_config_format(self):
         """
         Test if checker config option is meeting the reqired format.