Fix misleading error when missing problem statemetns

Author: gkreitz

problemtools/verifyproblem.py

@@ -754,9 +754,13 @@ def check(self, context: Context) -> bool:
         self._check_res = True
 
         if not self.statements:
-            allowed_statements = ', '.join(
-                f'problem.{ext}, problem.[a-z][a-z].{ext}' for ext in self.problem.format.statement_extensions
-            )
+            if self.problem.format is FormatVersion.LEGACY:
+                allowed_statements = ', '.join(
+                    f'problem.{ext}, problem.<language>.{ext}' for ext in self.problem.format.statement_extensions
+                )
+            else:
+                allowed_statements = ', '.join(f'problem.<language>.{ext}' for ext in self.problem.format.statement_extensions)
+
             self.error(
                 f'No problem statements found (expected file of one of following forms in directory {self.problem.format.statement_directory}/: {allowed_statements})'
             )